Diene rubber-inorganic compound composite and process for producing the same

ABSTRACT

An objective of the present invention is to provide a production process capable of improving an operation efficiency of a diene-based rubber-inorganic compound composite during production by forming a composite having high dispersibility of an inorganic compound in a diene-based rubber and having relatively large crumb diameter upon coagulation. The present invention provides a process for producing a composite comprising a diene-based rubber and an inorganic compound represented by the general formula: wM.xSiO y .zH 2 O (where M is at least one metal element selected from the group consisting of Al, Mg, Ti and Ca, metal oxide thereof or metal hydroxide thereof, and w, x, y, and z are an integer of from 1 to 5, an integer of from 0 to 10, an integer of from 2 to 5, and an integer of from 0 to 10, respectively.), and comprises a step of mixing the inorganic compound and/or a material capable of forming the inorganic compound, an anionic compound and a dispersion liquid of the diene-based rubber.

TECHNICAL FIELD

The present invention relates to a diene-based rubber-inorganic compoundcomposite and a production process therefor. More particularly, itrelates to a production process capable of improving an operationefficiency of a diene-based rubber-inorganic compound composite duringproduction by forming a composite having high dispersibility of aninorganic compound in a diene-based rubber and having relatively largecrumb diameter upon coagulation. In addition, the present inventionrelates to a diene-based rubber-inorganic compound composite in whichaluminium hydroxide is dispersed at high content and homogeneously, aswell as a production process therefor.

The diene-based rubber-inorganic compound composite produced by thepresent invention is utilized as a raw material for a rubber for a tiresuch as a tire tread, as well as various kinds of rubber products suchas a belt, a rubber roll and a hose, and has excellent wearingresistance.

BACKGROUND ART

An inorganic filler such as silica has been often used in combinationwith carbon black and the like as a reinforcing agent constituting arubber composition for a tire and the like. Such reinforcing agent isdry-kneaded together with a rubber component, and a rubber product suchas a tire is manufactured by using the resultant rubber composition.

In recent years, a method of producing a diene-based rubber-inorganiccompound composite where an inorganic compound is dispersedhomogeneously in the diene-based rubber has been disclosed (refer toJP-A-2002-241507) . This method involves a problem that the crumbdiameter of the obtained composite is as small as 500 μm or less andproblems being laborious for handing and poor in the operationefficiency during production steps for obtaining the diene-basedrubber-inorganic compound composite.

Further, a tire tread obtained by using a reinforcing agent where aninorganic filler such as silica is combined with carbon black and thelike shows low rolling resistance and excellent in operation stabilitytypically represented by wet skid resistance. However, it involvesproblems of being poor in wearing resistance and tensile strength of thevulcanized rubber.

In recent years, a rubber composition obtained by adding only analuminium hydroxide powder instead of the reinforcing agent describedabove and dry-kneading has been known (refer to the prior art forJP-A-2000-204197).

In addition, a rubber composition using silica and/or carbon black andaluminium hydroxide together (refer to JP-A-2000-204197 andJP-A-2000-302914), a rubber composition using silica, aluminiumhydroxide, magnesium hydroxide and the like (refer to JP-A-11-181155)and the like are also disclosed. These rubber compositions are alsoprepared by dry-kneading each of predetermined raw starting powders andinvolve problems that the dispersion of aluminium hydroxide and the likeis not enough and the resultant rubber products don't show sufficiencyin wearing resistance and tensile strength.

Further, the method disclosed in JP-A-2002-241507 leads to a lowformation yield of aluminium hydroxide and wearing resistance isimproved slightly.

Additionally, WO 02/20655A1 discloses a process for producing adiene-based-inorganic compound composite comprising mixing step of anaqueous dispersion containing a diene-based rubber and an aqueousdispersion of an inorganic compound. It is described that pH for theaqueous dispersion of the inorganic compound is preferably in the rangebetween 8.5 and 11 or between 2 and 4.

However, in a case where the inorganic compound constituting thecomposite is aluminium hydroxide, when coagulation is conducted, forexample, at pH in the range between 2 and 4 under a strong acidiccondition which is a usual coagulation condition for synthetic rubber, adiene-based rubber is light and suspends in the upper portion of anaqueous solution, whereas an inorganic compound containing aluminiumhydroxide is heavy and is precipitated by mixing of an aqueousdispersion of the diene-based rubber and an aqueous dispersion of theinorganic compound making it difficult for co-coagulation of rubber inwhich aluminium hydroxide is dispersed. In addition, when it is intendedto co-coagulate them effectively, it results in a problem of requiringmuch time for stirring, which is not efficiently.

Further, in a case wherein co-coagulation is conducted under a strongacidic condition, a large quantity of sulfuric acid has to be used forrendering the system acidic when sulfuric acid is used. And aluminiumsulfate and the like as by-products are precipitated in addition to theaimed aluminium hydroxide and they are intaken to the diene-based rubberto lower the content of aimed aluminium hydroxide relatively.

On the other hand, under an alkaline condition, a diene-based rubber ishard to coagulate, it is difficult to obtain a diene-basedrubber-aluminium hydroxide composite efficiently.

It was considered that in a case of using aluminium hydroxide solution,since a portion of aluminium hydroxide is precipitated within a weaklyacidic to weakly alkaline pH region to form a suspended state (state ofslurry), coagulation within the pH region described above is notpreferred.

DISCLOSURE OF THE INVENTION

The present invention is intended to solve the problems described aboveand an objective is to provide a production process capable of improvingan operation efficiency of a diene-based rubber-inorganic compoundcomposite during production by forming a composite having highdispersibility of an inorganic compound in a diene-based rubber andhaving relatively large crumb diameter upon coagulation, as well as adiene-based rubber-inorganic compound composite providing a rubberproduct outstandingly excellent in wearing resistance and a productionprocess therefor.

In addition, another objective of the present invention is to provide adiene-based rubber-inorganic compound composite having outstandinglyexcellent wearing resistance in which aluminium hydroxide is dispersedat high content and homogeneously, as well as a production processcapable of producing the composite efficiently in a short time. It isnoted that “Aluminium hydroxide” in the present invention includesAl(OH)₃, Al(OH)₄ ⁻ and Al₂O₃.nH₂O (n is an integer of 0 to 4) and isconverted as Al(OH)₃.

The present invention is described as follows.

-   1. A process for producing a diene-based rubber-inorganic compound    composite comprising a diene-based rubber and an inorganic compound    represented by the following general formula (I), comprising

a step of mixing an inorganic compound and/or a material capable offorming the inorganic compound, an anionic compound and a dispersionliquid of a diene-based rubber:wM.xSiO_(y) .zH₂O  (I)

wherein M is at least one metal element selected from the groupconsisting of Al, Mg, Ti and Ca, metal oxide thereof or metal hydroxidethereof, and w, x, y, and z are an integer of from 1 to 5, an integer offrom 0 to 10, an integer of from 2 to 5, and an integer of from 0 to 10,respectively.

-   2. The process for producing a diene-based rubber-inorganic compound    composite according to 1 above, wherein the material capable forming    the inorganic compound is at least one material selected from the    group consisting of metal salts, oxoacid salts of metals and organic    metal compounds.-   3. The process for producing a diene-based rubber-inorganic compound    composite according to 1 above, wherein the anionic compound is a    compound having a carboxyl group.-   4. The process for producing a diene-based rubber-inorganic compound    composite according to 3 above, wherein the compound having a    carboxyl group is at least one compound selected from the group    consisting of a rosinate and a salt of a fatty acid.-   5. The process for producing a diene-based rubber-inorganic compound    composite according to 1 above, wherein the dispersion liquid of the    diene-based rubber is a diene-based rubber latex synthesized by    emulsion polymerization.-   6. The process for producing a diene-based rubber-inorganic compound    composite according to 1 above, comprising a step of co-coagulating    the diene-based rubber and the inorganic compound from the liquid    mixture obtained in the mixing step by using an electrolyte    comprising a metal salt, a step of separating a coagulation product    by filtration, and a step of drying the coagulation product.-   7. The process for producing a diene-based rubber-inorganic compound    composite according to 1 above, wherein the diene-based rubber is a    diene-based rubber having a polar group.-   8. The process for producing a diene-based rubber-inorganic compound    composite according to 7 above, wherein the polar group is at least    one kind of group selected from the group consisting of hydroxyl    group, oxy group, alkoxysilyl group, epoxy group, carboxyl group,    carbonyl group, oxycarbonyl group, sulfide group, disulfide group,    sulfonyl group, sulfinyl group, thiocarbonyl group, imino group,    amino group, nitrile group, ammonium group, imide group, amide    group, hydrazo group, azo group and diazo group.-   9. The process for producing a diene-based rubber-inorganic compound    composite according to 1 above, wherein the inorganic compound    represented by the general formula (I) is an inorganic compound    represented by the following general formula (II):    Al₂O₃ .mSiO₂ .nH₂O  (II)

wherein m is an integer from 0 to 4 and n is an integer from 0 to 4.

-   10. The process for producing a diene-based rubber-inorganic    compound composite according to 2 above, wherein the metal    constituting the metal salt, the oxo acid salt of metal and the    organic metal compound is aluminium.-   11. The process for producing a diene-based rubber-inorganic    compound composite according to 1 above, further comprising a step    of mixing a dispersion liquid of a diene-based rubber to the liquid    mixture obtained in the mixing step.-   12. A diene-based rubber-inorganic compound composite which is    obtained by the process according to 1 above.-   13. A process for producing a diene-based rubber-inorganic compound    composite comprising a diene-based rubber and aluminium hydroxide,    comprising: a step of preparing an aluminium-containing suspension    whose pH is controlled in a range between 5.1 and 8.4, and a step of    mixing the aluminium-containing suspension and a dispersion liquid    of a diene-based rubber to co-coagulate the diene-based rubber and    aluminium hydroxide, successively.-   14. The process for producing a diene-based rubber-inorganic    compound composite according to 13 above, comprising a step of    adding at least one kind selected from the group consisting an acid    and a coagulation accelerator to the co-coagulated liquid mixture to    complete the co-coagulation.-   15. The process for producing a diene-based rubber-inorganic    compound composite according to 13 above, wherein the    aluminium-containing suspension is prepared by using an aluminium    salt containing an aluminate.-   16. The process for producing a diene-based rubber-inorganic    compound composite according to 13 above, wherein the dispersion    liquid of the diene-based rubber is a diene-based rubber latex by    emulsion polymerization.-   17. The process for producing a diene-based rubber-inorganic    compound composite according to 13 above, further comprising a step    of separating a coagulation product by filtration and a step of    drying the coagulation product.-   18. The process for producing a diene-based rubber-inorganic    compound composite according to 13 above, wherein the diene-based    rubber is a diene-based rubber having a polar group.-   19. The process for producing a diene-based rubber-inorganic    compound composite according to 18 above, wherein the polar group is    at least one kind of group selected from the group consisting of    hydroxyl group, oxy group, alkoxysilyl group, epoxy group, carboxyl    group, carbonyl group, oxycarbonyl group, sulfide group, disulfide    group, sulfonyl group, sulfinyl group, thiocarbonyl group, imino    group, amino group, nitrile group, ammonium group, imide group,    amide group, hydrazo group, azo group and diazo group.-   20. A diene-based rubber-inorganic compound composite which is    obtained by the process according to 13 above.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is described in detail.

A first process for producing a diene-based rubber-inorganic compoundcomposite according to the present invention is a process for producinga composite comprising a diene-based rubber and an inorganic compoundrepresented by the following general formula (I) and is characterized bycomprising a step of mixing an inorganic compound and/or a materialcapable of forming the inorganic compound, an anionic compound and adispersion liquid of a diene-based rubber.wM.xSiO_(y) .zH₂O  (I)(where M is at least one metal element selected from the groupconsisting of Al, Mg, Ti and Ca, metal oxide thereof or metal hydroxidethereof, and w, x, y, and z are an integer of from 1 to 5, an integer offrom 0 to 10, an integer of from 2 to 5, and an integer of from 0 to 10,respectively.)

The “Diene-based rubber” according to the present invention is notparticularly restricted providing it comprises a conjugated diene-basedmonomer unit as a monomer unit constituting a rubber, such as a(co)polymer comprised of a conjugated diene-based monomer and acopolymer comprised of a conjugated diene-based monomer and a monomerselected from the group consisting of a vinylic aromatic monomer and anolefinic unsaturated nitrile monomer. Specifically, the diene-basedrubber includes, for example, natural rubber, butadiene rubber, isoprenerubber, styrene-butadiene rubber, butadiene-isoprene rubber,butadiene-styrene-isoprene rubber, acrylonitrile-butadiene rubber,acrylonitrile-styrene-butadiene rubber, chloroprene rubber and the like.These may be used alone or in combination of two or more.

The diene-based rubber used in the present invention is preferably adiene-based rubber obtained by emulsion polymerization including, forexample, a butadiene rubber by emulsion polymerization, astyrene-butadiene rubber by emulsion polymerization, anacrylonitrile-butadiene rubber by emulsion polymerization, anacrylonitrile-butadiene rubber by emulsion polymerization and the like.

The diene-based rubber may be an oil-extended rubber where oil was addedto the rubber or it may be a non-oil-extended rubber. Further, anoil-extended rubber and a non-oil-extended rubber may be used incombination.

The “dispersion liquid of diene-based rubber” used in the productionprocess of the present invention is a dispersion in which thediene-based rubber exemplified above preferably is dispersed in anaqueous medium with no particular restriction. Further, this isapplicable also for a dispersion method of the exemplified diene-basedrubber. A dispersing medium is usually water, but it may be an aqueousmedium where alcohol is dissolved in water. As the dispersion liquid, adiene-based rubber latex obtained by emulsion polymerization ispreferred and includes natural rubber latex, an emulsion obtained byre-emulsification of a diene-based synthetic rubber, a diene-basedrubber emulsion formed by polymerization in an aqueous medium, adispersion liquid of a diene-based synthetic rubber and the like. Thesemay be used each alone or two or more of them may be used in combinationirrespective of the kind of the diene rubber and the kind of the liquiddispersant.

The conjugated diene-based monomer (hereinafter also referred to as“conjugated diene”) includes, for example, 1,3-butadiene,2,3-dimethyl-1,3-butadiene, 2-chloro-1,3-butadiene, 1,3-pentadiene,isoprene and the like. Among these, 1,3-butadiene, isoprene and the likeare preferred and 1,3-butadiene is more preferred. Further, theconjugated dienes may be used alone or in combination of two or more.

The vinylic aromatic monomer includes, for example, styrene,α-methylstyrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene,2,4-diisopropyl styrene, 2,4-dimethyl styrene, 4-tert-butyl styrene,5-tert-butyl-2-methylstyrene, monochlorostyrene, dichlorostyrene,monofluorostyrene and the like. Among these, styrene is preferred.Further, the vinylic aromatic monomers may be used alone or incombination of two or more.

The olefinic unsaturated nitrile monomer includes, for example,(meth)acrylonitrile, vinylidene cyanate and the like. These monomers maybe used alone or in combination of two or more.

As a diene-based rubber used in the production process of the presentinvention, not only the diene-based rubber comprising a monomer unitformed from the monomers described above but also a diene-based rubberhaving a polar group can also be used. In a case of using thisdiene-based rubber having the polar group, both a dispersibility of theinorganic compound contained in the resultant composite and areinforcing property of the resultant rubber products are improved.

As the polar group, a functional group having element including in thesecond period to fourth period and belonging to the groups 5B or 6B ofthe periodic table, specifically, a functional group having element suchas nitrogen, oxygen, sulfur and phosphorus, and, among all, a functionalgroup having element such as nitrogen and oxygen are preferred. Such apolar group includes, for example, a hydroxyl group, an oxy group, analkoxysilyl group, an epoxy group, a carboxyl group, a carbonyl group,an oxycarbonyl group, a sulfide group, a disulfide group, a sulfonylgroup, a sulfinyl group, a thiocarbonyl group, an imino group, an aminogroup, a nitrile group, an ammonium group, an imide group, an amidegroup, a hydrazo group, an azo group, a diazo group, anoxygen-containing heterocyclic group, a nitrogen-containing heterocyclicgroup, a sulfur-containing heterocyclic group and the like. Thediene-based rubber may have one polar group or have two or more polargroups. Further, among these groups, a hydroxyl group, an alkoxysilylgroup, an epoxy group, a carboxyl group, a sulfide group, a sulfonylgroup, an amino group, a nitrile group, a nitrogen-containingheterocyclic group and the like are preferred, a hydroxyl group, analkoxysilyl group, a carboxyl group, an amino group, a nitrile group, anitrogen-containing heterocyclic group and the like are furtherpreferred, and particularly, a hydroxyl group and an amino group aremost preferred.

A diene-based rubber having the polar group described above can beusually obtained by polymerizing a monomer such as a conjugated dieneand a vinylic monomer having the polar group described above.

The vinylic monomer having the polar group is not particularlyrestricted providing it is a polymerizable monomer having at least onepolar group described above in the molecule. That is, it may have two ormore polar groups in one molecule. In addition, it may have one or moredifferent polar groups in one molecule.

The vinylic monomer having the polar group includes, for example, avinylic monomer having a hydroxyl group, a vinylic monomer having analkoxysilyl group, a vinylic monomer having an epoxy group, a vinylmonomer having a carboxyl group, a vinylic monomer having an aminogroup, a vinylic monomer having a nitrile group and the like. Thesevinylic monomers may be used alone or in combination of two or more.

As the vinylic monomer having a hydroxyl group, a polymerizable monomerhaving at least one primary, secondary or tertiary hydroxyl group in onemolecule can be used. Such vinylic monomer having a hydroxyl groupincludes, for example, an unsaturated carboxylic acid-based monomerhaving a hydroxyl group, a vinylic aromatic monomer having a hydroxylgroup, a vinyl ether-based monomer having a hydroxyl group, a vinylketone-based monomer having a hydroxyl group, (meth)allyl alcohol andthe like. These may be used alone or in combination of two or more.Further, among these, the unsaturated carboxylic acid-based monomerhaving a hydroxyl group and the vinylic aromatic monomer having ahydroxyl group are preferred.

The unsaturated carboxylic acid-based monomer having a hydroxyl groupincludes a derivative of an ester, an amide, an anhydride and the likeof acrylic acid, methacrylic acid, itaconic acid, fumaric acid, maleicacid and the like. Among these, ester derivatives of acrylic acid,methacrylic acid and the like are preferred.

The unsaturated carboxylic acid-based monomer having a hydroxyl groupincludes, for example, a hydroxyalkyl (meth)acrylate such as2-hydroxyethyl (meth)acrylate, 2-hydroxylpropyl (meth)acrylate,3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate,3-hydroxybutyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate; amono(meth)acrylate of a polyalkylene glycol such as polyethylene glycoland polypropylene glycol (where the number of alkylene glycol unit is,for example, 2 to 23); an unsaturated amide having a hydroxyl group suchas N-hydroxymethyl (meth)acrylamide, N-(2-hydroxyethyl) (meth)acrylamideand N,N-bis(2-hydroxyethyl) (meth)acrylamide; and the like. Among these,hydroxyalkyl (meth)acrylate is preferred.

In addition, the vinylic aromatic monomer having a hydroxyl groupincludes, for example, o-hydroxystyrene, m-hydroxystyrene,p-hydroxystyrene, o-hydroxy-α-methylstyrene, m-hydroxy-α-methylstyrene,p-hydroxy-α-methylstyrene, p-vinylbenzyl alcohol and the like.

The vinylic monomer having an alkoxysilyl group includes, for example,(meth)acryloxymethyltrimethoxy silane,

-   (meth)acryloxymethylmethyldimethoxy silane,-   (meth)acryloxymethyldimethylmethoxy silane,-   (meth)acryloxymethyltriethoxy silane,-   (meth)acryloxymethylmethyldiethoxy silane,-   (meth)acryloxymethyldimethylethoxy silane,-   (meth)acryloxymethyltripropoxy silane,-   (meth)acryloxymethylmethyldipropoxy silane,-   (meth)acryloxymethyldimethylpropoxy silane,-   γ-(meth)acryloxypropyltrimethoxy silane,-   γ-(meth)acryloxypropylmethyldimethoxy silane,-   γ-(meth)acryloxypropyldimethyl methoxysilane,-   γ-(meth)acryloxypropyltriethoxy silane,-   γ-(meth)acryloxypropylmethyldiethoxy silane,-   γ-(meth)acryloxypropyldimethylethoxy silane,-   γ-(meth)acryloxypropyl tripropoxy silane,-   γ-(meth)acryloxypropylmethyl dipropoxy silane,-   γ-(meth)acryloxypropyl dimethyl propoxy silane,-   γ-(meth)acryloxypropylmethyl diphenoxy silane,-   γ-(meth)acryloxypropyl dimethylphenoxy silane,-   γ-(meth)acryloxypropylmethyl dibesiloxy silane,    γ-(meth)acryloxypropyldimethyl besiloxy silane; trimethoxy vinyl    silane, triethoxyvinyl silane, 6-trimethoxysilyl-1,2-hexene and    p-trimethoxysilyl styrene disclosed, for example, in JP-A-7-188356;    and the like. These vinylic monomers having an alkoxysilyl group may    be used alone or in combination of two or more.

The vinylic monomer having an epoxy group includes, for example,(meth)allyl glycidyl ether, glycidyl (meth)acrylate, 3,4-oxycyclohexyl(meth)acrylate and the like. These vinylic monomers having an epoxygroup may be used alone or in combination of two or more.

The vinylic monomer having a carboxyl group includes, for example, anester having a carboxyl group such as a monoester of an unsaturatedcarboxylic acid such as (meth)acrylic acid, maleic acid, fumaric acid,itaconic acid, tetraconic acid and sinnamic acid; or non-polymerizablepolybasic carboxylic acids such as phthalic acid, succinic acid andadipic acid, and an unsaturated compound having a hydroxyl group such as(meth)allyl alcohol and 2-hydroxyethyl (meth)acrylate, as well as saltsthereof. Among these, the unsaturated carboxylic acid is preferred.These vinylic monomers having a carboxyl group may be used alone or as acombination of two or more.

The vinylic monomer having an amino group may be used a polymerizablemonomer having at least one amino group selected from primary, secondaryand tertiary amino group in one molecule. Among these, a vinylic monomerhaving a tertiary amino group (such as a dialkylaminoalkyl(meth)acrylate and a vinylic aromatic compound having a tertiary aminogroup) are particularly preferred. Further, the vinylic monomer havingan amino group may be used alone or in combination of two or more.

The vinylic monomer having a primary amino group includes, for example,acrylamide, methacrylamide, aminomethyl (meth)acrylate, aminoethyl(meth)acrylate, aminopropyl (meth)acrylate, aminobutyl (meth)acrylate,p-aminostyrene and the like.

The vinyl monomer having a secondary amino group may be usedanilinostyrenes, anilinophenyl butadienes, N-mono-substituted(meth)acrylamides and the like.

The anilinostyrenes include, for example, anilinostyrene,β-phenyl-p-anilinostyrene, β-cyano-p-anilinostyrene,β-cyano-β-methyl-p-anilinostyrene, β-chloro-p-anilinostyrene,β-methyl-β-methoxycarbonyl-p-anilinostyrene, β-carboxy-p-anilinostyrene,β-methoxycarbonyl-p-anilinostyrene,β-(2-hydroxyethoxy)carbonyl-p-anilinostyrene, β-formyl-p-anilinostyrene,β-formyl-β-methyl-p-anilinostyrene,α-carboxy-β-carboxy-β-phenyl-p-anilinostyrene and the like.

The anilinophenyl butadienes may be used anilinophenyl butadienes andderivatives thereof and include, for example,1-anilinophenyl-1,3-butadiene, 1-anilinophenyl-3-methyl-1,3-butadiene,1-anilinophenyl-3-chloro-1,3-butadiene,3-anilinophenyl-2-methyl-1,3-butadiene,1-anilinophenyl-2-chloro-1,3-butadiene, 2-anilinophenyl-1,3-butadiene,2-anilinophenyl-3-methyl-1,3-butadiene,2-anilinophenyl-3-chloro-1,3-butadiene and the like.

In addition, N-mono-substituted (meth)acrylamides include, for example,N-methyl (meth)acrylamide, N-ethyl (meth)acrylamide, N-methylolacrylamide, N-(4-anilinophenyl) (meth)acrylamide and the like.

The vinylic monomer having a tertiary amino group may be usedN,N-di-substituted aminoalkyl acrylates, N,N-di-substituted aminoalkylacrylamides, a N,N-di-substituted aminoaromatic vinyl compound, a vinylcompound having a pyridyl group and the like.

The N,N-di-substituted amino acrylates include, for example, an ester ofacrylic acid or methacrylic acid such as N,N-dimethyl aminomethyl(meth)acrylate, N,N-dimethylaminoethyl (meth)acrylate,N,N-dimethylaminopropyl (meth)acrylate, N,N-dimethylaminobutyl(meth)acrylate, N,N-diethylaminoethyl (meth)acrylate,N,N-diethylaminopropyl (meth)acrylate, N,N-diethylaminobutyl(meth)acrylate, N-methyl-N-ethylaminoethyl (meth)acrylate,N,N-dipropylaminoethyl (meth)acrylate, N,N-dibutylaminoethyl(meth)acrylate, N,N-dibutylaminopropyl (meth)acrylate,N,N-dibutylaminobutyl (meth)acrylate, N,N-dihexylaminoethyl(meth)acrylate, N,N-dioctylaminoethyl (meth)acrylate, acryloylmorpholinand the like. Among these, N,N-dimethylaminoethyl (meth)acrylate,N,N-diethylaminoethyl (meth)acrylate, N,N-dipropylaminoethyl(meth)acrylate, N,N-dioctylaminoethyl (meth)acrylate,N-methyl-N-ethylaminoethyl (meth)acrylate and the like are preferred.

The N-N-di-substituted aminoalkyl acrylamides include, for example, anacrylamide compound or a methacrylamide compound such asN,N-dimethylaminomethyl (meth)acrylamide, N,N-dimethylaminoethyl(meth)acrylamide, N,N-dimethylaminopropyl (meth)acrylamide,N,N-dimethylaminobutyl (meth)acrylamide, N,N-diethylaminoethyl(meth)acrylamide, N,N-diethylaminopropyl (meth)acrylamide,N,N-diethylaminobutyl (meth)acrylamide, N-methyl-N-ethylaminoethyl(meth)acrylamide, N,N-dipropylaminoethyl (meth)acrylamide,N,N-dibutylaminoethyl (meth)acrylamide, N,N-dibutylaminopropyl(meth)acrylamide, N,N-dibutylaminobutyl (meth)acrylamide,N,N-dihexylaminoethyl (meth)acrylamide, N,N-dihexylaminopropyl(meth)acrylamide, N,N-dioctylaminopropyl (meth)acrylamide and the like.Among these, N,N-dimethylaminopropyl (meth)acrylamide,N,N-diethylaminopropyl (meth)acrylamide, N,N-dioctylaminopropyl(meth)acrylamide and the like are preferred.

The N-N-di-substituted aminoaromatic vinyl compounds include, forexample, a styrene derivative such as N,N-dimethylaminoethyl styrene,N,N-diethylaminoethyl styrene, N,N-dipropylaminoethyl styrene,N,N-dioctylaminoethyl styrene and the like.

In addition, a nitrogen-containing heterocyclic group may be used instead of an amino group and the nitrogen-containing heterocyclic groupincludes, for example, pyrrol, histidine, imidazol, triazolidin,triazole, triazine, pyridine, pyrimidine, pyrazine, indole, quinoline,purine, phenazine, pteridine, melamine and the like. Thesenitrogen-containing heterocycles may comprise other hetero atoms in thering.

Among the vinylic monomer having a nitrogen-containing heterocyclicgroup, the vinyl compound having a pyridyl group includes, for example,2-vinyl pyridine, 3-vinyl pyridine, 4-vinyl pyridine,5-methyl-2-vinylpyridine, 5-ethyl-2-vinylpyridine and the like. Amongthese, 2-vinyl pyridine, 4-vinyl pyridine and the like are preferred.Further, the vinylic monomers having a pyridyl group may be used aloneor in combination of two or more.

The vinylic monomer having a nitrile group includes, for example,(meth)acrylonitrile, vinylidene cyanide and the like. These monomershaving a nitrile group may be used alone or in combination of two ormore.

Contents of the monomer units constituting the diene-based rubber areproperly selected in accordance with required characteristics. When thetotal of the contents of the monomer units is 100% by mass, a content ofthe conjugated diene-based monomer unit is usually in a range from 40 to100% by mass, preferably from 50 to 90% by mass and more preferably from60 to 85% by mass, and a content of the vinylic aromatic monomer unit isusually in a range from 0 to 60% by mass, preferably from 10 to 50% bymass and more preferably from 15 to 40% by mass. Further, in a case of adiene-based rubber having a polar group, a content of the monomer unitformed from the monomer having a polar group is selected properly inaccordance with the degree of the monomer having a polar group and isusually from 0.01 to 20% by mass, preferably from 0.05 to 10% by mass.When the content of the monomer unit is less than 0.01% by mass, aninteraction with an inorganic compound constituting the composite issometimes decreased even in a case of using a monomer having a largepolarity, thereby failing to obtain a sufficient effect of the presentinvention. On the other hand, when the content is in excess of 20% bymass, the diene-based rubber having a polar group intensely aggregateswith an inorganic compound and tends to make a processing difficult. Ina case of using a diene-based rubber having the above contents themonomer units, it is possible to obtain a composite in which theinorganic compound is homogeneously dispersed therein and a rubbercomposition capable of providing a rubber product of outstandinglyexcellent wearing resistance.

The polymerization method for the diene-based rubber is not particularlyrestricted and may be used radical polymerization method, anionicpolymerization method and the like. The radial polymerization methodincludes, for example, bulk polymerization, suspension polymerization,emulsion polymerization and the like. Among these, emulsionpolymerization capable of obtaining a stable emulsified dispersionliquid upon completion of polymerization is particularly preferred sincethe dispersion liquid of diene-based rubber is used in the presentinvention. For the emulsion polymerization, known method can be applied.A diene-based rubber can be obtained, for example, by emulsifyingpredetermined monomers in an aqueous medium under the presence of anemulsifier, starting polymerization by a radical polymerizationinitiator, stopping polymerization by a polymerization terminator afterreaching a predetermined polymerization conversion and the like.

The emulsifier may be used an anionic surfactant, a nonionic surfactant,a cationic surfactant, an amphoteric surfactant and the like. Theseemulsifiers may be used alone or in combination of two or more. In orderto obtain a stable emulsified dispersion liquid, an anionic surfactantis usually used. The anionic surfactant including a salt of a longchained fatty acid having a number of carbon atoms of 10 or more, arosinate and the like is used. Specifically, a potassium salt or asodium salt of capric acid, lauric acid, myristic acid, palmitic acid,oleic acid, stearic acid and the like are included. In addition, afluorine-based surfactant can also be used.

The radical polymerization initiator includes, for example, an organicperoxide such as benzoyl peroxide, lauroyl peroxide, tert-butylhydroperoxide, cumene hydroperoxide, paramenthane hydroperoxide,di-tert-butyl peroxide and dicumyl peroxide. Additionally, adiazocompound such as azobisisobutylonitrile; an inorganic peroxide suchas potassium persulfate, a redox type catalyst such as combination ofthe peroxide described above with ferrous sulfate and the like can alsobe used. These radical polymerization initiators may be used alone or incombination of two or more.

A chain transfer agent may be used for controlling molecular weight ofthe diene-based rubber. The chain transfer agent includes, for example,an alkyl mercaptan such as tert-dodecyl mercaptan andn-dodecylmercaptan; carbon tetrachloride; thioglycols; diterpene,terpinolene, γ-terpinenes, α-methylstyrene dimer and the like.

In the polymerization of the diene-based rubber by emulsionpolymerization, monomers, an emulsifier, a radical polymerizationinitiator, a chain transfer agent and the like may be collectivelycharged entirely to a reaction vessel to start polymerization, or eachof the ingredients may be added by being supplied continuously orintermittently during proceeding of the reaction. The diene-based rubberaccording to the present invention can be polymerized by using a reactorremoved with oxygen at a temperature usually in a range from 0 to 100°C., preferably from 0 to 80° C. Operation condition such as temperatureand stirring may be changed properly in the course of the reaction. Thepolymerization method may be continuous or batchwise.

In addition, large polymerization conversion may lead to a gelation andit is preferable that the polymerization conversion is restricted to 80%or less and it is particularly preferred to stop the polymerization in arange from 30 to 70% of the polymerization conversion. Thepolymerization is stopped by adding a polymerization terminator at thetime reaching a predetermined polymerization conversion. Thepolymerization terminator includes an amine compound such as hydroxylamine and diethylhydroxyl amine, a quinone compound such ashydroquinone, and the like. After the stopping of polymerization,unreacted monomers are removed from a reaction system as required by amethod such as steam distillation to prepare a latex where a diene-basedrubber is dispersed.

In the invention, the latex described above may be used as it is, or alatex dispersed as an oil-extended rubber by addition of an extendingoil for rubber may also be used for the dispersion liquid of thediene-based rubber. The extending oil for rubber is not particularlyrestricted and includes, for example, naphthenic, paraffinic, aromaticprocess oils and the like. The amount of the extending oil for rubber tobe used for preparing the oil-extended rubber is preferably from 5 to100 parts by mass and preferably, from 10 to 60 parts by mass based on100 parts by mass of the diene-based rubber contained in the latex.

Mooney viscosity [ML₁₊₄(100° C.)] of the diene-based rubber oroil-extended rubber contained in the dispersion liquid of thediene-based rubber is preferably in a range from 10 to 200 and morepreferably from 30 to 150. In a case where the Mooney viscosity is lessthan 10, physical properties including wearing resistance are notsufficient and exceeding 200 leads to a poor workability and a difficultkneading.

Next, the “inorganic compound represented by the general formula (I)”according to the present invention is usually in a fine particle form,which is dispersed homogeneously in the diene-based rubber to form acomposite combined with the diene-based rubber.wM.xSiO_(y) .zH₂O  (I)(wherein M is at least one metal element selected from the groupconsisting of Al, Mg, Ti and Ca, metal oxide thereof or metal hydroxidethereof, and w, x, y, and z are an integer of from 1 to 5, an integer offrom 0 to 10, an integer of from 2 to 5, and an integer of from 0 to 10,respectively.)

The inorganic compound described above does not include metal per se.

The inorganic compound includes, for example, alumina (Al₂O₃) such asγ-alumina and α-alumina, alumina monohydrate (Al₂O₃.H₂O) such asboehmite and diaspore, aluminium hydroxide (Al(OH)₃) such as gibbsiteand bayerite, magnesium oxide (MgO), magnesium hydroxide (Mg(OH)₂),calcium oxide (CaO), calcium hydroxide (Ca(OH)₂), aluminium magnesiumoxide (MgO.Al₂O₃), titanium white such as rutile and anatase, titaniumblack (TiO_(2n−1)), calcined clay (Al₂O₃.2SiO₂), kaolin(Al₂O₃.2SiO₂.H₂O), pyrophyllite (Al₂O₃.4SiO₂.H₂O), bentonite(Al₂O₃.4SiO₂.2H₂O), talc (3MgO.4SiO₂.H₂O), attapulgite(5MgO.8SiO₂.9H₂O), magnesium calcium silicate (CaMgSiO₄), aluminiumsilicate (Al₂Si₂O₅(OH)₄ such as Al₂O₃.2SiO₂.2H₂O), magnesium silicate(MgSiO₃), calcium silicate (CaO.SiO₂.yH₂O), crystalline aluminosilicatecontaining hydrogen, alkali metal or alkaline earth metal forcompensating electric charges such as various types of zeolite and thelike. These inorganic compounds may be used alone or in combination oftwo or more.

Among the inorganic compounds described above, an inorganic compoundrepresented by the following general formula (II) is preferred.Al₂O₃ .mSiO₂ .nH₂O  (II)(where m is an integer from 0 to 4 and n is an integer from 0 to 4.)

The inorganic compound includes, for example, alumina such as γ-aluminaand α-alumina, alumina monohydrate such as boehmite or diaspore,aluminium hydroxide such as gibbsite or bayerite, calcined clay,kaolinite, pyrophyllite, bentonite and the like. These inorganiccompounds may be used alone or in combination of two or more.

The inorganic compound has a particle diameter of preferably 10 μm orless and more preferably 3 μm or less. If the particle size of theinorganic compound is excessively large, destruction property andwearing resistance of rubber products may sometimes be worsened.

The amount of the inorganic compound to be used is preferably from 5 to200 parts by mass, more preferably from 5 to 67 parts by mass andfurther preferably from 7 to 60% by mass based on 100 parts by mass ofthe diene-based rubber contained in the dispersion liquid of thediene-based rubber. In a case the amount of the inorganic compound islittle, an improvement in gripping performance on wet road surfacebecomes difficult to be obtained in the form of a tire product. On theother hand, in a case the amount is too much, it is not preferredresulting in a problem of sometimes making a production of the compositedifficult, and even when it can be produced, a problem of worseningdispersibility of the inorganic compound in the diene-based rubber orhardening the composite remarkably occurs.

When a diene-based rubber-inorganic compound composite is produced byusing the inorganic compound described above, the inorganic compound maybe used as it is for the purpose of previously mixing with othermaterials, or it may be used being dissolved or dispersed in an aqueousmedium such as water. In the latter case, a colloid mill, a vibratingmill, a homogenizer, a dyno-mill, a ball mill, a tube mill, a supermixer and the like can be used.

In order to use the inorganic compound represented by the generalformula (I) described above as the inorganic compound constituting thecomposite, a material capable of forming the above inorganic compound(hereinafter also referred to as “inorganic compound-forming material”)can also be used as a starting material for production in the presentinvention.

The inorganic compound-forming material may be either an inorganicsubstance or an organic-based substance. The inorganic substance may beused a metal salt, a salt of oxo acid comprising metal and the like,including (1) aluminium salt such as aluminium chloride, aluminiumnitrate, aluminium sulfate, basic aluminium chloride, basic aluminiumsulfate and polyaluminium chloride, (2) calcium nitrite, calciumnitrate, calcium chloride, magnesium chloride (hexahydrate), magnesiumnitrate (hexahydrate), magnesium sulfate, titanium trichloride, titaniumtetrachloride and the like, (3) aluminate such as sodium aluminate(aluminium salt of oxo acid) and the like. These compounds may be usedalone or in combination of two or more.

These compounds may be used in the form being dissolved or dispersed inwater, acid, alkali or the like.

Further, these compounds may be used with addition of silicon salt (suchas silicon chloride) and/or silicon salt of oxo acid (silicate such assodium silicate) . In this case, silicate, aluminium salt or aluminatemay be used as a same aqueous solution or respective aqueous solutionsmay be prepared separately and used.

On the other hand, the organic-based substance may be used an organicmetal compound and an alkoxide comprising various metal is preferable.The organic-based substance includes triethoxy aluminium, tripropoxyaluminium, diethoxy magnesium, dipropoxy magnesium, tetraethoxytitanium, tetrapropoxy titanium, a compound having a hydrolizablehalogen atom such as chlorine by substituting in at least one of thecompound, and the like. These compounds may be used alone or incombination of two or more.

These organic metal compounds are usually used in a state beingdissolved in an organic solvent, for example, a water soluble alcoholsuch as ethanol, methanol and isopropyl alcohol. Accordingly, a solutioncomprising an inorganic compound-forming material is obtained by addingwater to a solution of the organic metal compound thereby hydrolyzingthe organic metal compound and then condensating the hydrolyzates. Inthe reaction of the organic metal compound and water, an acidic materialor an alkaline material may be added optionally in order to promote thecondensation reaction. These materials may be added also as an aqueoussolution of acid or alkali.

The organic-based substance obtained as described above, a solutioncomprising the organic-based substance or a dispersion liquid containingthe organic-based substance may also be used in admixture with asolution comprising the inorganic substance or a dispersion liquidcomprising the inorganic substance. When the substance is used,controlling pH and the like may also be conducted optionally.

Further, the inorganic compound-forming material can be used incombination with the inorganic compound.

For obtaining the inorganic compound represented by the general formula(II) as the inorganic compound described above, an aluminium-containingsolution where an aluminium salt of a salt of an inorganic acid and/or asalt of an organic acid, an organic aluminium salt and the like aredissolved or dispersed in water, an acid or an alkali or the like can beused. Most of the compounds correspond to the inorganic compound-formingmaterial described above.

The salt of an inorganic acid and the salt of an organic acid include,for example, an aluminate such as sodium aluminate; a salt of an oxoacid such as sulfate, sulfite, hyposulfite, nitrate, nitrite,hyponitrite, chlorate, chlorite, hypochlorite, bromate, bromite,hypobromite, phosphate, phosphite, hypophosphite, acetate, succinate,phthalate and hexanoate; a salt of a hydroacid such as a salt ofhydrochloric acid (chloride, polychloride); an aluminosilicate and thelike. Further, these may be used alone or in combination of two or more.

The above compound that is insoluble to a medium such as water, an acidand an alkali may be used in a state of dispersing the same in themedium. A colloid mill, a homogenizer and the like exemplified above canbe used in dispersing.

In addition, a dispersion liquid of the above compound which is preparedby the following methods and the like can be also used.

-   (1) One prepared by gelling a basic aluminium salt under heating and    neutralizing it with a base.-   (2) Alumina gel as obtained by mixing an aluminium salt such as    aluminium chloride and an aluminate, and neutralizing them.-   (3) One prepared by reacting an aluminate and a mineral acid, or    reacting an aluminium salt such as aluminium sulfate and an alkali    such as sodium hydroxide to aluminium hydroxide, and finely    dispersing precipitates of aluminium hydroxide by stirring while    shearing into an aqueous medium such as water.-   (4) Alumina sol obtained by peptizing an alumina gel prepared from    sodium aluminate, aluminium sulfate or the like as described in    Japanese Examined Patent Publication No. Sho 40-8409.

Further, among the organic aluminium salt described above, the abovealuminium alkoxide including, for example, trimethoxy aluminium,triethoxy aluminium, tripropoxy aluminum, tributoxy aluminum and thelike is preferable. In addition, a compound where an alkoxyl groupconstituting the compound is substituted with a halogen atom such aschlorine may be used. These may be used alone or in combination of twoor more.

The aluminium-containing solution obtained as described above may beused alone or in combination of two or more. Additionally, one preparedby using the aluminium salt and other prepared by using an organicaluminium salt may also be used in combination (for example, a solutionprepared by using an aluminate and a solution prepared by using anorganic aluminium salt mixed at an optional ratio).

Further, the inorganic compound-forming material described above may bethe one obtained by applying an alkali treatment to a simple substancemetal (Al, Mg, Ti or Ca) of metal element constituting the generalformula (I).

The amount of the inorganic compound-forming material to be used isselected such that the amount of the inorganic compound of the generalformula (I) or (II) to be formed is, preferably from 5 to 200 parts bymass, more preferably from 5 to 67 parts by mass and further preferablyfrom 7 to 60 parts by mass based on 100 parts by mass of the diene-basedrubber contained in the dispersion liquid of the diene-based rubber. Ina case of forming a composite containing the inorganic compound by usingthe inorganic compound-forming material, the amount of use may beselected while taking it into consideration of byproducts to beincorporated. Also in a case of using the inorganic compound-formingmaterial and the inorganic compound described above together, the amountof use for both of them may be selected by the same method.

The feature of the production process of the diene-basedrubber-inorganic compound composite according to the prevent inventionis to comprise a step of mixing the dispersion liquid of the diene-basedrubber, the inorganic compound and/or the inorganic compound-formingmaterial and, further, an anionic compound.

The anionic compound is not particularly restricted providing it has anegative charge. The anionic compound includes, for example, an anionicsurfactant having a carboxyl group, a sulfonate group, a phosphate groupand the like. In the present invention, a compound having a carboxylgroup is particularly preferred. “Carboxyl group” means herein —COOH and—COO⁻. In addition, the number of the carboxyl group present in onemolecule of the compound is not also restricted. The compound includes arosinate, and a salt of a fatty acid exemplified as the anionicsurfactant (emulsifier) in the explanation for the diene-based rubber, anaphthenate, an ether carboxylate, an alkenyl succinate, anN-acylsalcinate, N-acylglutaminate and the like. These may be used aloneor in combination of two or more.

The rosinate includes, for example, alkali metal salt, alkaline earthmetal salt and ammonium salt of rosin acid and the like. The alkalimetal atom includes, for example, lithium, sodium, potassium and thelike. As the rosinate used in the present invention, potassium salt ispreferred.

The salt of a fatty acid includes, for example, potassium salt, sodiumsalt, lithium salt, ammonium salt and lower amine salt of a fatty acidhaving from 10 to 20 carbon atoms, and the like. Among these, apalmitate, a stearate, a laurate, a linolate and a linolenate arepreferred.

The anionic compound may be used as it is (solid or the like), or in astate dissolved or dispersed in a dispersion liquid of the diene-basedrubber, a dispersion liquid or a solution of the inorganic compound oran aqueous medium constituting a dispersion liquid or a solution of theinorganic compound-forming material.

The amount of the anionic compound to be used is preferably from 0.5 to10 parts by mass and more preferably from 1 to 6 parts by mass based on100 parts by mass of the diene-based rubber contained in the dispersionliquid of the diene-based rubber. When the amount of use of the anioniccompound is little, the obtained diene-based rubber-inorganic compoundcomposite is sometimes excessively small.

Since the anionic compound is also used for the production of adispersion liquid of a diene-based rubber as described above, an excessanionic compound during production of the diene-based rubber may also beused.

In the “step of mixing the inorganic compound and/or the materialcapable of forming the inorganic compound, the anionic compound and thedispersion liquid of the diene-based rubber” in the production processof the present invention, the mixing method is not particularlyrestricted. That is, each of the ingredients may be collectively mixed,or those mixed divisionally may be finally mixed collectively. Preferredmixing methods are, for example, (1) a method of mixing the inorganiccompound and/or the inorganic compound-forming material and the anioniccompound, and then mixing the same with the dispersion liquid of thediene-based rubber, (2) a method of mixing the inorganic compound and/orthe inorganic compound-forming material and a portion of the dispersionliquid of the diene-based rubber, mixing this mixture with the anioniccompound, and further mixing the same with the remaining portion of thedispersion liquid of the diene-based rubber, (3) a method of mixing thedispersion liquid of the diene-based rubber and the anionic compound,and then further mixing this mixture with the inorganic compound and/orthe inorganic compound-forming material, and the like.

Then, when a diene-based rubber-inorganic compound composite isrecovered from the above mixture, a general method for coagulating arubber component from a latex may be applied to recover a coagulationproduct. And it may be recovered by removing the aqueous medium by themethod of heating, depressurization or the like. The former method leadsto more homogeneous diene-based rubber-inorganic compound composite,being preferable. In a case where an extending oil for rubber is blendedpreviously to the dispersion liquid of the diene-based rubber, anoil-extended rubber-inorganic compound composite is recovered bycoagulation.

The coagulation method is to add (1) an aqueous solution of sodiumchloride or potassium chloride, (2) an aqueous solution of a salt ofpolyvalent metal including calcium, magnesium, zinc and aluminium, suchas calcium chloride, magnesium chloride, zinc chloride, aluminiumchloride, calcium nitrate, magnesium nitrate, zinc nitrate, aluminiumnitrate, magnesium sulfate, zinc sulfate and aluminium sulfate, as anelectrolyte constituent component and/or (3) optionally hydrochloricacid, nitric acid, sulfuric acid and the like, whereby a diene-basedrubber-inorganic compound composite can be coagulated as a crumb. Thesesubstances may be used alone or in combination of two or more. In thisstep, fine inorganic compound can also be coagulated by using apolymeric coagulant (anionic, nonionic and cationic, particularly,anionic or nonionic type) and the like. Temperature, pH and the likeupon co-coagulation are not particularly restricted. And for the purposeof reducing inorganic salts remaining in the diene-basedrubber-inorganic compound composite to be produced, conditions arecontrolled so that temperature is 10° C. or higher, preferably in arange from 10 to 80° C. and more preferably from 10 to 50° C., and pHvalue (pH value at 25° C.) is in a range between 2 and 14 (morepreferably, between pH 4 and 11). When the temperature is lower than 10°C., it does not tend to be industrially suitable. On the other hand,when the temperature is excessively high, no large crumbs may beobtained. Large composite can be obtained by co-coagulation within alower temperature range among the preferred temperature range describedabove.

After co-coagulation of the diene-based rubber and the inorganiccompound, the emulsifier, the electrolyte and the like are removedusually by water-washing the coagulation products and then water wasremoved by hot blow drying or vacuum drying to conduct drying. With theprocedures described above, a composite where the inorganic compound isuniformly dispersed in the diene-based rubber can be obtained.

A number-average particle diameter of the diene-based rubber-inorganiccompound composite produced according to the present invention isusually from 1 to 50 mm and preferably from 3 to 20 mm. In a case wherethe particle diameter of the diene-based rubber-inorganic compoundcomposite is in a range described above, crumbs capable of improving theoperation efficiency during production can be obtained.

A second process for producing a diene-based rubber-inorganic compoundcomposite (hereinafter also referred to as “diene-based rubber-aluminiumhydroxide composite”) according to the present invention is process forproducing a composite comprising a diene-based rubber and aluminiumhydroxide and is characterized by comprising a step of preparing analuminium-containing suspension controlled to between pH 5.1 and 8.4,and a step of mixing the aluminium-containing suspension and adispersion liquid of a diene-based rubber thereby co-coagulating thediene-based rubber and aluminium hydroxide, successively.

The diene-based rubber described above is the same as the diene-basedrubber in the explanation for the first production process of thediene-based rubber-inorganic compound composite.

In the following, the “aluminium-containing suspension” is to bedescribed.

The aluminium-containing suspension is not particularly restrictedproviding pH is in a range between 5.1 and 8.4, preferably between 5.5and 8.3, more preferably between 6.0 and 8.0 and particularly preferablybetween 6.5 and 7.5 and providing the suspension comprises an ingredientcapable of forming aluminium hydroxide. And the suspension may be onewhere an Al ingredient (aluminium ion, ion of aluminium compound and thelike) is dissolved or one where an aluminium compound is contained whiledispersing.

A specific example of the aluminium-containing suspension includes onewhere an aluminium salt is dissolved or dispersed in water, an acid oran alkali, one that a solution of an organic metal compound (organicaluminium compound) and the like controlled to pH in a range between 5.1and 8.4. In controlling pH, an acid (such as sulfuric acid, hydrochloricacid) or an alkali (such as sodium hydroxide, potassium hydroxide) andthe like can be used.

Irrespective of the contained Al component state (chemical state), it isnecessary to control pH of the aluminium-containing suspension in arange between 5.1 and 8.4 before mixing with the dispersion liquid ofthe diene-based rubber. In addition, since the aluminium-containingsuspension sometimes precipitates partially, it is preferably stirred inorder to prevent formation of precipitates during or after controllingpH.

In a case where pH of the aluminium-containing suspension is less than5.1, a yield of aluminium hydroxide in the obtained composite tends tobe lowered. On the other hand, in a case where pH exceeds 8.4, acoagulation of the diene-based rubber is incomplete and the diene-basedrubber and an aluminium compound containing aluminium hydroxide tend tobe separated even when an acid is added for completing the coagulation.

The aluminium salt may be either a salt of an inorganic acid or a saltof organic acid. The salt of an inorganic acid and the salt of anorganic acid include, for example, an aluminate such as sodiumaluminate; a salt of an oxo acid such as sulfate, sulfite, hyposulfite,nitrate, nitrite, hyponitrite, chlorate, chlorite, hypochlorite,bromate, bromite, hypobromite, phosphate, phosphite, hypophosphite,acetate, succinate, phthalate and hexanoate; a salt of a hydroacid suchas a salt of hydrochloric acid (chloride, polychloride); alumina (Al₂O₃)such as γ-alumina and α-alumina; alumina monohydrate (Al₂O₃.H₂O) such asboehmite and diaspore; aluminium hydroxide (Al(OH)₃) such as gibbsiteand bayerite; aluminium magnesium oxide (MgO.Al₂O₃); aluminium silicate(Al₂Si₂O₅, Al₂O₃.2SiO₂.2H₂O and the like); an aluminosilicate and thelike. Further, these may be used alone or in combination of two or more.

The above aluminium salt that is insoluble to a medium such as water, anacid and an alkali may be used in a state of dispersing the same in themedium by stirring under shearing. A colloid mill, a vibration mill, ahomogenizer, a dyno-mill, a ball mill, a tube mill a super mixer and thelike can be used in stirring under shearing.

In addition, a dispersion liquid of the aluminium salt which is preparedby the following method and the like can be also used.

-   (1) One prepared by gelling a basic aluminium salt under heating and    neutralizing it with a base.-   (2) Alumina gel as obtained by mixing an aluminium salt such as    aluminium chloride and an aluminate, and neutralizing them.-   (3) One prepared by reacting an aluminate and a mineral acid, or    reacting an aluminium salt such as aluminium sulfate and an alkali    such as sodium hydroxide to aluminium hydroxide, and dispersing    precipitates of aluminium hydroxide finely by stirring while    shearing into an aqueous medium such as water.-   (4) Alumina sol obtained by peptizing an alumina gel prepared from    sodium aluminate, aluminium sulfate or the like as described in    Japanese Examined Patent Publication No. Sho 40-8409.

Among the aluminium salts, an aluminate (such as sodium aluminate) whichis easily soluble in water is preferred. While sodium aluminate exhibitsstrong alkalinity when dissolved in water and pH can be controlled byadding an acid such as sulfuric acid and hydrochloric acid.

Further, among the organic aluminium compounds described above, thealuminium alkoxide including, for example, trimethoxy aluminium,triethoxy aluminium, tripropoxy aluminum, tributoxy aluminum and thelike is preferable. In addition, a compound where an alkoxyl groupconstituting the compound is substituted with a halogen atom such aschlorine may be used. These may be used alone or in combination of twoor more.

The organic aluminium compound is usually used in a state beingdissolved in an organic solvent, for example, a water soluble alcoholsuch as ethanol, methanol and isopropyl alcohol. Accordingly, a solutioncomprising an Al component is obtained by adding water to a solution ofthe organic metal compound thereby hydrolyzing the organic metalcompound and then condensing the hydrolyzate. In the reaction of theorganic metal compound and water, an acid or an alkali may be addedoptionally in order to promote the condensation reaction. These may beadded also as an aqueous solution of acid or alkali. By controlling thepH of the solution, the aluminium-containing suspension according to thepresent invention can be prepared.

The obtained aluminium-containing suspension may be used alone or incombination of two or more. Further, one prepared by using an aluminiumsalt and one prepared by using a metal aluminium compound may also beused in combination (for example, a suspension prepared by using analuminate and a suspension prepared by using an organic aluminiumcompound at an optional ratio).

Further, the aluminium-containing suspension may sometimes exhibit aslurry state in a case where pH is in a range between 5.1 and 8.4. Inthis state and also in a completely dissolved state, mixing thealuminium-containing suspension with the dispersion liquid of thediene-based rubber described above can be proceeded.

In “the step of mixing an aluminium-containing suspension and adispersion liquid of the diene-based rubber thereby coagulating thediene-based rubber and aluminium hydroxide” in the present invention, amethod of mixing a dispersion of the diene-based rubber and aaluminium-containing suspension is particularly restricted. Thesuspension and the dispersion liquid may be collectively mixed or may bemixed while being added divisionally. In batchwise production, a methodof continuously adding a dispersion liquid of a diene-based rubber to analuminium-containing suspension is preferred. In addition, in continuousproduction, an example of preferred method is continuously adding adispersion liquid of a diene-based rubber to an aluminium-containingsuspension so as to keep a predetermined content ratio between aluminiumhydroxide and the diene-based rubber constituting a composite. Themixing temperature is usually in a range between 10 and 80° C.,preferably between 20 and 60° C., and further preferably between 30 and50° C.

In the mixing of a dispersion liquid of a diene-based rubber and analuminium-containing suspension, it is preferred that the solid contentof the diene-based rubber contained in the dispersion liquid of thediene-based rubber and the amount of Al contained in thealuminium-containing suspension (being converted as Al₂O₃) arecontrolled to the range described below. That is, Al₂O₃ is preferably ina range from 3 to 130 parts by mass and more preferably from 5 to 100parts by mass based on 100 parts by mass of the diene-based rubber. In acase where the amount is insufficient, effect as filler is notsufficient. On the other hand, in a case where it is excessive, effectas rubber tends to be insufficient.

Although coagulation starts in the instant of mixing analuminium-containing suspension and a dispersion liquid of a diene-basedrubber and a coagulation product comprising the diene-basedrubber-aluminium hydroxide composite (hereinafter also referred to as“crumb”) is formed, coagulation is not sometimes completed in a casewhere pH of the mixed solution increases due to the effect of thedispersion liquid of the diene-based rubber which is usually alkaline(clouding remains in the liquid mixture). In such a case, to add anacid, a coagulation accelerator and the like is preferable forcompleting the coagulation. In a case of adding the acid, it is desiredthat sulfuric acid or hydrochloric acid, preferably, sulfuric acid isused to control pH in a range between 5.0 and 8.0. In this case, when pHis lowered to less than pH5.0, the content of the resultant aluminiumhydroxide is deteriorated. After completion of the coagulation (afterclouding of the liquid mixture disappears), pH may be lower than 5.0.Further, the coagulation accelerator includes an electrolyte solutionand the like.

The electrolyte solution described above includes (1) an aqueoussolution of sodium chloride or potassium chloride, (2) an aqueoussolution of a salt of polyvalent metal including calcium, magnesium,zinc and aluminium, such as calcium chloride, magnesium chloride, zincchloride, aluminium chloride, calcium nitrate, magnesium nitrate, zincnitrate, aluminium nitrate, magnesium sulfate, zinc sulfate andaluminium sulfate, and/or, (3) optionally hydrochloric acid, nitricacid, sulfuric acid and the like. Among these, a salt of polyvalentmetal including calcium, magnesium and aluminium is preferable, andparticularly, calcium chloride, magnesium chloride, magnesium sulfateand the like are preferred. These substances may be used alone or incombination of two or more. In this step, fine alminium hydoroxide canalso be coagulated by using a polymeric coagulant (anionic, nonionic andcationic, particularly, anionic or nonionic type) and the like.

Subsequently, it goes to a step of recovering the diene-basedrubber-aluminium hydroxide composite as a coagulation product.

After co-coagulation of the diene-based rubber and aluminium hydroxide,the emulsifier, the electrolyte and the like are removed usually bywater-washing the coagulation products and then water was removed by hotblow drying or vacuum drying to conduct drying. With the proceduresdescribed above, a composite where aluminium hydroxide is uniformlydispersed in the diene-based rubber can be obtained.

In addition, a method of removing the aqueous medium from the mixturecomprises a method of cast-drying the mixture and then applying vacuumdrying and a drying method using a drum dryer.

A content of aluminium hydroxide contained in the diene-basedrubber-aluminium hydroxide composite produced according to the presentinvention is preferably from 5 to 200 parts by mass and more preferablyfrom 7 to 150 parts by mass based on 100 parts by mass of the rubbercomponents. Other inorganic compounds than aluminium hydroxide usuallyincludes a salt comprising an anion used for the controlling pH of thealuminium-containing suspension and an aluminium ion, for example,aluminium sulfate.

Further, a particle diameter of the diene-based rubber-aluminiumhydroxide composite is usually from 10 μm to 50 mm and preferably from50 μm to 20 mm.

And a number-average particle diameter of aluminium hydroxideconstituting the diene-based rubber-inorganic compound compositeproduced according to the present invention can be 500 nm or less,preferably from 1 to 300 nm and more preferably 5 to 100 nm and furtherpreferably from 5 to 50 nm.

The diene-based rubber-inorganic compound composite produced by thefirst and second production processes for the diene-basedrubber-inorganic compound composite according to the present inventioncan be used together with an additive for a preparation of a rubbercomposition. As the additive, a crosslinking agent including avulcanizing agent, a filler for reinforcing, other fillers, a couplingagent, a vulcanization accelerator, fatty acids and the like areblended. In addition, other rubber components, other diene-basedrubber-inorganic compound composites may be blended optionally.

The crosslinking agent includes a vulcanizing agent such as sulfur and asulfur-containing compound or a non-sulfur type crosslinking agent suchas a peroxide. Among these, the former type vulcanizing agent,particularly, sulfur is preferred. An amount of the vulcanizing agent tobe blended is usually from 0.5 to 10 parts by mass and particularlypreferably from 1 to 6 parts by mass based on 100 parts by mass of theentire amount of the rubber component.

The filler for reinforcing includes, for example, carbon black, silicaand the like.

The carbon black includes, for example, channel black, furnace black,acetylene black, thermal black and the like depending on the productionprocess and any of them may be used. In addition, one having a nitrogenadsorption specific surface area (BET value measured according to ASTM D3037-88) of 70 m²/g or more and a dibutyl phthalate oil absorptionamount of 90 ml/100 g or more (JIS K 6221-1982 (A method) is preferred.

In a case where the BET value is less than 70 m²/g, a sufficient wearingresistance is difficult to occur. In a case where the BET value isexcessive, it causes worsening of fuel consumption by a tire. A morepreferred range of the BET value is from 90 to 180 m²/g in view ofwearing resistance and fuel consumption.

Additionally, in a case where the DBP value is less than 90 ml/100 g, asufficient wearing resistance can not be obtained. In a case where theDBP value is excessive, it causes deterioration of elongation at breakof rubber products. In view of wearing resistance and fuel consumption,a more preferred range for the DBP value is from 100 to 180 ml/100 g.

As silica, one used so far for reinforcing a rubber, for example, a dryprocess silica, a wet process silica (hydrous silicic acid) and the likecan be used. Among these, the wet process silica is preferred. Silicahaving the nitrogen adsorption specific surface area (BET value) in arange from 100 to 300 m²/g is preferred in view of wearing resistance,fuel consumption and the like. The BET value is a value measured afterdrying at 300° C. for 1 hour according to ASTM D 4820-93.

As the filler for reinforcing, only carbon black may be used or onlysilica may be used. Further, carbon black and silica may be usedtogether. Further, an amount of the reinforcing filler to be blended is,preferably from 5 to 100 parts by mass, more preferably from 30 to 85parts by mass based on 100 parts by mass of the entire amount of therubber component, with a view point of balance for wearing resistance,wet performance and fuel consumption.

Other fillers include, for example, clay, calcium carbonate, magnesiumcarbonate and the like. These may be used alone or in combination of twoor more.

The coupling agent is not particularly restricted and a silane couplingagent is preferred. The silane coupling agent includes, for example,vinyl trichloro silane, vinyl triethoxy silane, vinyltris(β-methoxy-ethoxy) silane, β-(3,4-epoxy cyclohexyl)-ethyltrimethoxysilane, γ-glycidoxypropyl trimethoxy silane, γ-glycidoxypropylmethyldiethoxy silane, γ-methacryloxypropyl trimethoxy silane,N-(β-aminoethyl)-γ-aminopropyl trimethoxy silane,N-(β-aminoethyl)-γ-aminopropylmethyl dimethoxy silane,N-phenyl-γ-aminopropyltrimethoxy silane, γ-chloropropyl trimethoxysilane, γ-mercaptopropyl trimethoxy silane, γ-aminopropyl trimethoxysilane, bis-(3-(triethoxysilyl)propyl) tetrasulfide,bis-(3-(triethoxysilyl)propyl) disulfide, γ-trimethoxysilylpropyldimethyl thiocarbamyl tetrasulfide, γ-trimethoxysilylpropyl benzothiazyltetrasulfide and the like. These may be used alone or in combination oftwo or more. When the coupling agent is blended, wearing resistance ortan δ is more improved.

An amount of the coupling agents to be blended is preferably 20 parts bymass or less and more preferably 15 parts by mass or less (usually 1part by mass or more) based on 100 parts by mass of the entire amount ofthe inorganic compound contained in the rubber composition or the totalamount together with the inorganic filler such as the reinforcing fillerwhen it is blended additionally.

The vulcanization accelerator includes each of the compounds such asaldehyde ammonia-based, guanidine-based, thiourea-based, thiazole-basedand dithiocarbamic acid-based. These may be used alone or in combinationof two or more. An amount of the vulcanization accelerator to be blendedis preferably from 0.5 to 15 parts by mass and particularly preferablyfrom 1 to 10 parts by mass based on 100 parts by mass of the entireamount of the rubber component.

The fatty acids include, for example, a fatty acid and an ester compoundthereof. These may be used alone or in combination of two or more.

The fatty acid is preferably a higher fatty acid and is usually amono-carboxylic acid with a number of carbon atoms usually of 10 or more(preferably 12 or more, and usually 20 or less), which may be asaturated fatty acid or an unsaturated fatty acid, with the saturatedfatty acid being preferred in view of the weather resistance. The fattyacid includes, for example, palmitic acid, stearic acid, lauric acid,oleic acid, linolic acid, linolenic acid and the like.

Further, as the ester compound of the fatty acid, an ester of a higherfatty acid and an alcohol compound is preferred. The number of carbonatoms of the alcohol compound is preferably from about 1 to 10. Inaddition, an ester of a higher alcohol (with the number of carbon atomsof about 10 or more, and about 20 or less) of a lower fatty acid (withthe number of carbon atoms of about 1 to 10) can also be used.

The “other rubber component” described above means other rubber which isnot constituting the composite and includes, for example,styrene-butadiene rubber, butadiene rubber, isoprene rubber,butadiene-isoprene rubber, butadiene-styrene-isoprene rubber,acrylonitrile-butadiene rubber, acrylonitrile-styrene-butadiene rubber,acrylic rubber, butyl rubber, natural rubber, chloroprene rubber and thelike which are obtained by known methods. The rubber component describedabove may have a polar group. The rubber component may be anoil-extended rubber by an extending oil for rubber.

In addition to the additives described above, an extending oil forrubber, zinc oxide, a vulcanization aid, an anti-aging agent, aprocessing aid and the like can be blended properly.

The diene-based rubber-inorganic compound composite produced accordingto the present invention leads to a rubber product by the followingmanner. That is, the composite described above and, optionally, otherrubber components, a reinforcing agent such as silica, carbon black andcarbon-silica dual phase filler, an extending oil and other blendingagents are kneaded by using a kneader such as a Banbury mixer at atemperature of 70 to 180° C. After that, a kneading product is cooledand a vulcanizing agent such as sulfur, a vulcanization accelerator andthe like are blended by using a Banbury mixer or a mixing roll toprepare a rubber composition, which is then molded into a predeterminedshape. Then, they were vulcanized at a temperature of 140 to 180° C. toobtain a required vulcanized rubber, that is, a rubber product.

The rubber composition has a favorable processability and the obtainedvulcanized rubber has excellent tensile strength, wearing resistance,wet skid resistance, impact resilience and is suitable particularly to atire tread.

BEST MODE FOR CARRYING OUT THE INVENTION

The present invention is to be described more specifically withexamples. In Examples and Comparative examples, parts and % are on themass basis unless otherwise specified.

1. Preparation of Diene-Based Rubber (Oil-Extended Diene-Based Rubberand Non-Oil-Extended Diene-Based Rubber)

1-1. Oil-Extended Diene-Based Rubber

To a nitrogen-replaced polymerization vessel, were charged 200 parts ofwater, 4.5 parts of rosin acid soap, predetermined amounts of butadieneand other monomers shown in Table 1 (total monomer is 100 parts.), and0.3 part of tert-dodecyl mercaptan. Then, temperature of thepolymerization vessel was set to 5° C., and polymerization was startedby adding 0.1 part of p-menthane hydroperoxide as a polymerizationinitiator, 0.07 part of sodium ethylenediamine tetraacetate, 0.05 partof ferrous sulfate 7 hydrate and 0.15 part of sodium formaldehydesulfoxylate. When the polymerization conversion reached 60%, diethylhydroxylamine was added to stop polymerization. Then, unreacted monomerswere recovered by steam stripping and an aqueous dispersion containing adiene-based rubber of about 21% solid content was obtained.

After that, for the aqueous dispersion of the diene-based rubberobtained by using the monomers shown in Table 1, 37.5 parts of aromaticoil (trade name; “Fukkol Aromax #3” manufactured by Fujikosan Co. Ltd.)based on 100 parts of the solid content of the contained diene-basedrubber was blended, which was coagulated with sulfuric acid and sodiumchloride to obtain crumbs. Then, the crumbs were washed with water anddried by a hot blow drier to obtain an oil-extended diene-based rubber(a to j in Table 1).

Contents of the monomer units constituting the oil-extended diene-basedrubber obtained as described above and Mooney viscosity of theoil-extended diene-based rubber were measured by methods describedbelow, and the results were shown together in Table 1.

-   (a) Bound styrene content (% by mass); it was determined by    preparing a calibration curve according to an infrared absorption    spectral method.-   (b) Bound content of the monomer having carboxyl group (% by mass);    it was determined by conducting an operation of dissolving rubber in    toluene and reprecipitating the same with methanol twice thereby    purifying the same and, after vacuum drying, dissolving the rubber    into chloroform and then neutralizing titration.-   (c) Bound content of the monomer having amino group or nitrile group    (% by mass); it was determined by conducting an operation of    dissolving rubber in toluene and reprecipitating the same with    methanol twice thereby purifying the same and, after vacuum drying,    applying elemental analysis and calculating the content based on the    nitrogen content.-   (d) Bound content of the monomer having hydroxyl group (% by mass);    it was determined by conducting an operation of dissolving rubber in    toluene and reprecipitating the same with methanol twice thereby    purifying the same and, after vacuum drying, measuring by 270 MHz    ¹H-NMR.-   (e) Bound content of butyl acrylate (% by mass); it was determined    by conducting an operation of dissolving rubber in toluene and    reprecipitating the same with methanol twice thereby purifying the    same and, after vacuum drying, measuring by 270 MHz ¹³C-NMR.-   (f) Bound content of the monomer having alkoxysilyl group (% by    mass); it was determined by conducting an operation of dissolving    rubber in toluene and reprecipitating the same with methanol twice    thereby purifying the same and, after vacuum drying, measuring by    270 MHz ¹H-NMR.

(g) Mooney viscosity [ML₁₊₄ (100° C.)]; it was measured according to JISK 6300-1994 under the condition at a measuring temperature of 100° C.,preheating for one minute and by measurement for 4 minutes. TABLE 1Oil-extended diene-based rubber a b c d e f g h i j Charged amountButadiene 58 57.5 57 57 66 57 57 51 56 57.5 (parts by mass) Styrene 4242 42 42 26 42 42 42 42 42 Acrylonitrile 8 2-Hydroxyethyl methacrylate0.5 Diethylaminoethyl methacrylate 1 4-Vinylpyridine 1 Methacrylic acid1 Itaconic acid 1 Butyl acrylate 7 Methacrylamide 2 γ-methacryloxypropylmethacrylate 0.5 Bound content Styrene 35 35 35 35 20 35 35 35 35 35 (%by mass) Acrylonitrile 10 2-Hydroxyethyl methacrylate 0.3Diethylaminoethyl methacrylate 0.7 4-Vinylpyridine 0.6 Methacrylic acid0.8 Itaconic acid 0.6 Butyl acrylate 4 Methacrylamide 0.9γ-methacryloxypropyl methacrylate 0.4 Extending oil (parts by mass) 37.537.5 37.5 37.5 37.5 37.5 37.5 37.5 37.5 37.5 Mooney viscosity 50 48 5152 52 49 48 53 51 52 of oil-extended diene-based rubber1-2. Non-Oil-Extended Diene Rubber

To a nitrogen-replaced polymerization vessel, were charged 200 parts ofwater, 4.5 parts of rosin acid soap, predetermined amounts of butadieneand other monomers shown in Table 2 (total monomer is 100 parts.), and0.3 part (in a case of using styrene) or 0.7 part (in a case of notusing styrene) of tert-dodecyl mercaptan. Then, temperature of thepolymerization vessel was set to 5° C., and polymerization was startedby adding 0.1 part of p-menthane hydroperoxide as a polymerizationinitiator, 0.07 part of sodium ethylenediamine tetraacetate, 0.05 partof ferrous sulfate 7 hydrate and 0.15 part of sodium formaldehydesulfoxylate. When the polymerization conversion reached 60%, diethylhydroxylamine was added to stop polymerization. Then, unreacted monomerswere recovered by steam stripping and an aqueous dispersion containing adiene-based rubber of 21% solid content was obtained.

After that, the aqueous dispersion was coagulated with sulfuric acid andsodium chloride to obtain crumbs. Then, the crumbs were washed withwater and then dried by a hot blow dryer to obtain a diene-based rubber(k to t in Table 2). Contents of the monomer units constituting thediene-based rubber and Mooney viscosity of the diene-based rubber weremeasured in the same manner as that for the oil-extended diene-basedrubber described above and the results were shown together in Table 2.TABLE 2 Non-oil-extended diene-based rubber k l m n o p q r s t Chargedamount Butadiene 72 71.5 71 76 71 100 92 99.5 99 99 (parts by mass)Styrene 28 28 28 16 28 Acrylonitrile 8 8 2-Hydroxyethyl methacrylate 0.50.5 Diethylaminoethyl methacrylate 1 1 Itaconic acid 1 1 Bound contentStyrene 23.5 23.5 23.5 13 23.5 (% by mass) Acrylonitrile 10 102-Hydroxyethyl methacrylate 0.3 0.3 Diethylaminoethyl methacrylate 0.70.7 Itaconic acid 0.6 0.6 Mooney viscosity of 50 47 51 48 52 48 50 50 5249 non-oil-extended diene-based rubber2. Production of Diene-Based Rubber-Inorganic Compound Composite (I)

The oil-extended diene-based rubber and non-oil-extended diene-basedrubber obtained as described above and natural rubber latex “NR” (tradename; “HA” manufactured by Felder Rubber Co., solid content; 62%) wereused such that the total amount for the respective rubber components was100 parts, and production of the diene-based rubber-inorganic compoundcomposites was conducted such that the content ratio for the rubbercomponent and each of the inorganic compounds to be contained have thevalues shown in Table 3 in order to form five types of compositeconstitutions (i) to (v) shown in Table 3. For example, in a case ofTable 3 (i), they are properly controlled so that a composite containing30 parts of the inorganic compound based on 137.5 parts of theoil-extended diene-based rubber containing 100 parts of diene-basedrubber is produced.

As the inorganic compound, those shown below were used.

-   (1) Aluminium hydroxide (gibbsite): trade name; “HIGILITE H-43M”    manufactured by Showa Denko K. K., average particle diameter; 0.6    μm.-   (2) Alumina monohydrate (beohmite): trade name; “PURAL 200”    manufactured by Condea Japan Co., average particle diameter; 0.14    μm.-   (3) γ-Alumina: trade name; “Baikalox CR125” manufactured by    Baikowski Co., average particle diameter; 0.3 μm.-   (4) Fired clay: trade name; “POLYFIL 40” manufactured by J. M. Huber    Co., average particle diameter; 1.2 μm.-   (5) Kaolinite: trade name; “POLYFIL DL”, manufactured by J. M. Huber    Co., average particle diameter; 1.0 μm.-   (6) Magnesium hydroxide: trade name; “KISUMA 5A” manufactured by    Kyowa Kagaku Kogyo K. K., average particle diameter; 0.8 μm.

(7) Titanium oxide (anatase): trade name; “TIPAQUE A-100” manufacturedby Ishihara Sangyo Co., average particle diameter; 0.15 μm TABLE 3Composite constitution (i) (ii) (iii) (iv) (v) Rubber componentOil-extended diene-based rubber; 137.5* (parts by mass) a˜j Oil-extendeddiene-based rubber; 137.5* a, b, c, e, g Non-oil-extended diene-based100 100 rubber; k˜o Non-oil-extended diene-based 70 rubber; p˜t NR 30Inorganic compound (parts by mass) 30    20  50 30   20*It contains 100 parts by mass of diene-based rubber.2-1. Method by Homogenizer

EXAMPLE 1

For the composite constitution (i) shown in Table 3, 539 parts of anemulsion containing 137.5 parts of the oil-extended diene-based rubber(comprising 100 parts of a diene-based rubber) obtained as describedabove, a dispersion liquid prepared by dispersing 30 parts of thealuminium oxide (gibbsite) as the inorganic compound in 200 parts ofwater by using a homogenizer and 2 parts of potassium rosinate werestirred and mixed at 25° C.

After that, sulfuric acid was added to the resultant mixture and theywere coagulated with sodium chloride while controlling pH of the mixeddispersion liquid to in a range between 4 and 5, to form crumbs. A sizeof the crumb was 8 mm or more and was equivalent to a size of the crumbcomprising styrene-butadiene rubber produced by usual emulsionpolymerization.

Then, the resultant crumbs were washed with water and were dried by ahot blow drier to obtain an oil-extended diene-based rubber-inorganiccompound composite (refer to Table 5). The resultant composite was ashedby heating at 640° C. for 8 hours using an electric furnace. The amountof the inorganic compound calculated based on the ash content was 30parts being converted as inorganic compound based on 100 parts of thediene-based rubber.

“◯” of “Diameter of coagulated crumb” in Table 5 means a case where thenumber-average particle diameter was 5 mm or more. This is the same inthe following cases.

EXAMPLES 2 TO 40

For the composite constitution (i) shown in Table 3, oil-extendeddiene-based rubber-inorganic compound composites were produced in thesame manner as Example 1 while changing the kinds of the oil-extendeddiene-based rubber and the inorganic compound. A size for each of theobtained crumbs was 5 mm or more.

EXAMPLES 136 TO 155

For the composite constitution (iv) shown in Table 3, oil-extendeddiene-based rubber-inorganic compound composites were produced in thesame manner as Example 1 while changing the kinds of the oil-extendeddiene-based rubber and the inorganic compound. A size for each of theobtained crumbs was 5 mm or more.

The results of Examples 1 to 10 using aluminium hydroxide for thecomposite constitution (i) in Table 3 were shown in Table 5. AndExamples 11 to 15 using alumina monohydrate were shown in Table 6,Examples 16 to 20 using γ-alumina were shown in Table 7, Examples 21 to25 using calcined clay were shown in Table 8, Examples 26 to 30 usingkaolinite were shown in Table 9, Examples 31 to 35 using magnesiumhydroxide were shown in Table 10, and Examples 36 to 40 using titaniumoxide were shown in Table 11, respectively.

In addition, the results of Examples 136 to 140 using aluminiumhydroxide for the composite constitution (iv) in Table 3 were shown inTable 24, Examples 141 to 145 using alumina monohydrate were shown inTable 25, Examples 146 to 150 using γ-alumina were shown in Table 26,and Examples 151 to 155 using calcined clay were shown in Table 27,respectively.

COMPARATIVE EXAMPLE 1

An oil-extended diene-based rubber-inorganic compound composite wasproduced without addition of potassium rosinate in the same manner asExample 1. A size of crumb was measured by a light scattering typeparticle size distribution measuring apparatus (manufactured by HoribaLtd.) and was 700 μm.

EXAMPLES 71 TO 105, EXAMPLES 116 TO 125, AND EXAMPLES 166 TO 175

For composite constitution (ii) or (iii) shown in Table 3, 476 parts ofan aqueous dispersion containing 100 parts of the non-oil-extendeddiene-based rubber obtained as described above, a dispersion liquidprepared by dispersing 20 parts or 50 parts of each of the inorganiccompounds in 200 parts of water by using a homogenizer and 3 parts ofpotassium rosinate were stirred and mixed at 25° C.

After that, sulfuric acid was added to the resultant mixture and theywere coagulated with sodium chloride while controlling pH of the mixeddispersion liquid in a range between 4 and 5, to form crumbs. An averagediameter of the crumb was 5 mm or more and was equivalent to a size ofthe crumb comprising styrene-butadiene rubber produced by usual emulsionpolymerization. Subsequent procedures were conducted in the same manneras Example described above, to obtain non-oil-extended diene-basedrubber-inorganic compound composites. The resultant composite was ashedby heating at 640° C. for 8 hours using an electric furnace. Each of theamounts of the inorganic compounds calculated from the ash content was20 parts or 50 parts being converted as the inorganic compound based on100 parts of the diene-based rubber.

The results of Examples 71 to 75 using aluminium hydroxide for thecomposite constitution (ii) in Table 3 were shown in Table 13. AndExamples 76 to 80 using alumina monohydrate were shown in Table 14,Examples 81 to 85 using γ-alumina were shown in Table 15, Examples 86 to90 using calcined clay were shown in Table 16, Examples 91 to 95 usingkaolinite were shown in Table 17, Examples 96 to 100 using magnesiumhydroxide were shown in Table 18, and Examples 101 to 105 using titaniumoxide were shown in Table 19, respectively.

The results of Examples 116 to 120 using aluminium hydroxide for thecomposite constitution (iii) in Table 3 were shown in Table 21 andExamples 121 to 125 using aluminium hydrate were shown in Table 22,respectively.

In addition, the results of Examples 166 to 170 using aluminiumhydroxide for the composite constitution (v) in Table 3 were shown inTable 29 and Examples 171 to 175 using aluminium monohydrate were shownin Table 30, respectively.

2-2. Method by In-Situ (I)

EXAMPLE 41

For the composite constitution (i) shown in Table 3, 380 parts of 10%sulfuric acid was added to 2,570 parts of an aqueous 2.4% solution ofsodium aluminate (0.9% being converted as Al₂O₃) and pH was controlledto 7, to obtain an aluminium-containing slurry solution comprisingaluminium hydroxide as a main component. After that, 3 parts ofpotassium rosinate was added and stirred sufficiently at 25° C. Then,this liquid mixture, and an emulsion which is containing 100 parts ofthe diene-based rubber and 37.5 parts of an aromatic oil, and is havingsolid concentration of 21% were mixed under stirring to form a slurrycomprising crumbs. A size of the crumb was 10 mm.

The obtained crumbs were washed with water and were dried by a hot blowdrier to obtain an oil-extended diene-based rubber-inorganic compoundcomposite. The introduction amount of the inorganic compound calculatedbased on the ash component of the obtained composite was 30 parts beingconverted as aluminium hydroxide (Al(OH)₃).

EXAMPLES 42 TO 50, EXAMPLES 106 TO 110, EXAMPLES 126 TO 130, EXAMPLES156 TO 160 AND EXAMPLES 176 TO 180

For five kinds of composite constitutions (i) to (v) shown in Table 3,oil-extended diene-based rubber-inorganic compound composites ornon-oil-extended diene-based rubber-inorganic compound composites wereproduced in the same manner as Example 41 by using an emulsion ofoil-extended diene-based rubber or an aqueous dispersion ofnon-oil-extended diene-based rubber (each containing 100 parts of adiene-based rubber).

The results of Examples 41 to 50 for the composite constitution (i) inTable 3 were shown in Table 12. And Examples 106 to 110 for thecomposite constitution (ii) were shown in Table 20, Examples 126 to 130for the composite constitution (iii) were shown in Table 23, Examples156 to 160 for the composite constitution (iv) were shown in Table 28and Examples 176 to 180 for the composite constitution (v) were shown inTable 31, respectively.

COMPARATIVE EXAMPLE 2

An oil-extended diene-based rubber-inorganic compound composite wasproduced without addition of potassium rosinate in the same manner asExample 41. A size of crumb was measured by the above particle sizedistribution measuring apparatus and was 320 μm.

2-3. Method by In-Situ (II)

EXAMPLE 51

For the composite constitution (i) shown in Table 3, 380 parts of 10%sulfuric acid was added to 2,570 parts of an aqueous 2.4% solution ofsodium aluminate (0.9% being converted as Al₂O₃) and pH was controlledto 7, to obtain an aluminium-containing slurry solution comprisingaluminium hydroxide as a main component. After that, 30% of a prescribedamount of an emulsion which is containing 100 parts of the diene-basedrubber and 37.5 parts of an aromatic oil, and is having solidconcentration of 21%, and the above aluminium-containing slurry solutionwere mixed while stirring at 25° C. to form a slurry comprising crumbs.Then 3 parts of potassium rosinate and the remaining 70% of the aboveemulsion were added to the slurry and further mixed to form crumbs. Asize of the crumb was 9 mm. The resultant crumbs were treated in thesame manner as the Example described above to obtain an oil-extendeddiene-based rubber-inorganic compound composite (refer to Table 12).

EXAMPLES 52 TO 60

Oil-extended diene-based rubber-inorganic compound composites wereproduced by using emulsions containing the oil-extended diene-based b toj (containing 100 parts of a diene-based rubber) shown in Table 1 in thesame manner as Example 51 (refer to Table 12).

COMPARATIVE EXAMPLE 3

An oil-extended diene-based rubber-inorganic compound composite wasproduced without addition of potassium rosinate in the same manner asExample 51. A size of crumb was measured by the above particle sizedistribution measuring apparatus and was 280 μm.

2-4. Method by In-Situ (III)

EXAMPLE 61

For the composite constitution (i) shown in Table 3, 500 parts of 10%sulfuric acid was added to an aqueous solution prepared by adding 95parts of sodium hydroxide to 2,660 parts of an aqueous 3.4% solution ofaluminium sulfate (0.9% being converted as Al₂O₃) and controlled to pH14, and pH was controlled to 7 to obtain an aluminium-containing slurrysolution comprising aluminium hydroxide as a main component. After that,3 parts of potassium rosinate was added and stirred sufficiently at 25°C. Then, this liquid mixture, and an emulsion which is containing 100parts of diene-based rubber and 37.5 parts of aromatic oil, and ishaving solid concentration of 21% were mixed under stirring to form aslurry comprising crumbs. A size of the crumb was 8 mm. The resultantcrumbs were treated in the same manner as in the Example described aboveto obtain an oil-extended diene-based rubber-inorganic compoundcomposite (refer to Table 12).

EXAMPLES 62 TO 70, EXAMPLES 111 TO 115, EXAMPLES 131 TO 135, EXAMPLES161 TO 165 AND EXAMPLES 181 TO 185

For five kinds of composite constitutions (i) to (v) shown in Table 3,oil-extended diene-based rubber-inorganic compound composites ornon-oil-extended diene-based rubber-inorganic compound composites wereproduced in the same manner as Example 61 by using an emulsion ofoil-extended diene-based rubber or an aqueous dispersion ofnon-oil-extended diene-based rubber (each containing 100 parts of adiene-based rubber).

The results of Examples 61 to 70 for the composite constitution (i) inTable 3 were shown in Table 12. And Examples 111 to 115 for thecomposite constitution (ii) were shown in Table 20, Examples 131 to 135for the composite constitution (iii) were shown in Table 23, Examples161 to 165 for the composite constitution (iv) were shown in Table 28and Examples 181 to 185 for the composite constitution (v) were shown inTable 31, respectively.

COMPARATIVE EXAMPLE 4

An oil-extended diene-based rubber-inorganic compound composite wasproduced in the same manner as in Example 61 except for not usingpotassium rosinate. A size of crumb was measured by the above particlesize distribution measuring apparatus and was 250 μm.

3. Preparation of Rubber Composition

Rubber compositions were prepared by using composites produced inExamples 1 to 185 described above and ingredients described below, andkneading two stages to be described below in accordance with theformulations A to E in Table 4. The “Inorganic compound” in Table 4means each kind of the inorganic compound contained in the composites.

-   (1) “N339”; carbon black, trade name; “SEAST KH” manufactured by    Tokai Carbon Co., LTD.-   (2) “Silica”; silica, trade name; “NIPSIL AQ” manufactured by Nippon    Silica Industrial Co., LTD.-   (3) “Aromatic oil”; trade name; “Fukkol Aromax #3” manufactured by    Fujikosan Co. Ltd.-   (4) “Stearic acid”; trade name; “LUNAC S-30” manufactured by Kao    Corp.-   (5) “6C”; N-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine,    anti-aging agent, trade name; “NOCRACK 6C” manufactured by    Ouchishinko Chemical Industrial Co. Ltd.-   (6) “Si69”; bis(triethoxysilylpropyl)tetrasulfan, silane coupling    agent, trade name; “Si69” manufactured by Degussa Co.-   (7) “DPG”; diphenyl guanizine, vulcanization accelerator, trade    name; “NOCCELER-D” manufactured by Ouchishinko Chemical Industrial    Co. Ltd.-   (8) “DM”; dibenzothiazyl sulfide, vulcanization accelerator, trade    name; “NOCCELER-DM” manufactured by Ouchishinko Chemical Industrial    Co. Ltd.-   (9) “NS”; N-tert-butyl-2-benzothiazoyl sulpheneamide, vulcanization    accelerator, trade name; “NOCCELER-NS-F” manufactured by Ouchishinko    Chemical Industrial Co. Ltd.    (Kneading Method in First Stage)

Ingredients at the first stage were kneaded at a maximum temperature of160° C. by a kneading apparatus (trade name; “LABOPLASTMILL”manufactured by Toyo Seiki Seisaku-Sho, Ltd.) in accordance with theformulation shown in Table 4.

(Kneading Method at Second Stage)

Ingredients at the second stage were added to the kneading product asdescribed above and kneaded by the above apparatus. The maximumtemperature during kneading was 100° C.

In addition, as Comparative Examples 5 to 119, rubber compositions wereprepared by using oil-extended diene-based rubbers a to j ornon-oil-extended diene-based rubbers k to t, and commercially availablealuminium hydroxide powder (trade name; “HIGILITE H-43M” manufactured byShowa Denko K. K., average particle diameter; 0.6 μm) by dry blending inaccordance with the formulation in Table 6. TABLE 4 Formulation A B C DE 1st kneading step Oil-extended diene-based rubber; 137.5 (parts bymass) a˜j Oil-extended diene-based rubber; 137.5 a, b, c, e, gNon-oil-extended diene-based 100 100 rubber; k˜o Non-oil-extendeddiene-based 70 rubber; p˜t NR 30 Inorganic compound 30 20 50 30 20 N33960 40 30 40 Silica 30 Aromatic oil 10 10 10 Stearic acid 2 2 2 2 2 6C 11 1 1 1 Si69 3 1 2nd kneading ZnO 3 3 3 3 3 step DPG 0.8 0.8 1.2 0.8 0.8(parts by mass) DM 1 1 1.5 1 1 NS 1 1 1 1 1 Sulfur 1.5 1.5 1.5 1.5 1.54. Evaluation of Performance

The rubber compositions prepared as described above were heat-treated at160° C. for 15 minutes to obtain vulcanized products. The vulcanizedproducts were used for specimens to be measured and the followingevaluations were conducted.

-   (1) T_(B); tensile strength was measured according to JIS K6251-1993    by using No. 3 type test specimen under a conditions at a measuring    temperature of 25° C. and at a tensile speed of 500 mm/minutes. The    unit is MPa.-   (2) Wearing resistance; abrasion loss at a slip ratio of 25% was    calculated by using a Lambourn type wearing tester. A reciprocal for    the abrasion loss at a measuring temperature of 25° C. was indicated    as an index based on 100 for the Comparative Example of the same    series. The wearing resistance is better as the index is larger.

The foregoing results are shown in Tables 5 to 31.

The results of Examples 1 to 10 and 41 to 70 using aluminum hydroxide asthe inorganic compound for the formulation A in Table 4 were shown inTables 5 and 12. And Examples 11 to 15 using alumina monohydrate wereshown in Table 6, Examples 16 to 20 using γ-alumina were shown in Table7, Examples 21 to 25 using calcined clay were shown in Table 8, Examples26 to 30 using kaolin were shown in Table 9, Examples 31 to 35 usingmagnesium hydroxide were shown in Table 10 and Examples 36 to 40 usingtitanium oxide were shown in Table 11, respectively.

The results of Examples 71 to 75 and 106 to 115 using aluminum hydroxideas the inorganic compound for the formulation B in Table 4 were shown inTables 13 and 20. And Examples 76 to 80 using alumina monohydrate wereshown in Table 14, Examples 81 to 85 using γ-alumina were shown in Table15, Examples 86 to 90 using calcined clay were shown in Table 16,Examples 91 to 95 using kaolin were shown in Table 17, Examples 96 to100 using magnesium hydroxide were shown in Table 18 and Examples 101 to105 using titanium oxide were shown in Table 19, respectively.

The results of Examples 116 to 120 and 126 to 135 using aluminumhydroxide as the inorganic compound for the formulation C in Table 4were shown in Tables 21 and 23, and Examples 121 to 125 using aluminamonohydrate were shown in Table 22, respectively.

The results of Examples 136 to 140 and 156 to 165 using aluminumhydroxide as the inorganic compound for the formulation D in Table 4were shown in Tables 24 and 28. And Examples 141 to 145 using aluminamonohydrate were shown in Table 25, Examples 146 to 150 using γ-aluminawere shown in Table 26 and Examples 151 to 155 using calcined clay wereshown in Table 27, respectively.

The results of Examples 166 to 170 and 176 to 185 using aluminumhydroxide as the inorganic compound for the formulation E in Table 4were shown in Tables 29 and 31, and Examples 171 to 175 using aluminamonohydrate were shown in Table 30, respectively. TABLE 5 [Compositeconstitution (i) using aluminium hydroxide] Example Dispersion-in-watermethod 1 2 3 4 5 6 7 8 9 10 Oil-extended diene-based rubber a b c d e fg h i j Diameter of coagulated crumb ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ EvaluationT_(B) (MPa) 21.5 23.2 23.6 23.1 23.4 23.1 23.8 23.4 22.9 24.4 Wearingresistance 122 130 128 130 138 134 132 129 131 138 Comparative exampleDry blending 5 6 7 8 9 10 11 12 13 14 Oil-extended diene-based rubber ab c d e f g h i j Evaluation T_(B) (MPa) 20.1 21.7 21.4 21.3 21.6 21.021.4 20.9 21.1 22.1 Wearing resistance 100 110 109 108 115 107 109 108108 113

TABLE 6 [Composite constitution (i) using alumina monohydrate]Dispersion-in-water method Example 11 Example 12 Example 13 Example 14Example 15 Oil-extended diene-based rubber a b c e g Diameter ofcoagulated crumb ◯ ◯ ◯ ◯ ◯ Evaluation T_(B) (MPa) 24.7 25.5 25.6 25.125.8 Wearing resistance 112 125 116 120 122 Comparative ComparativeComparative Comparative Comparative Dry blending example 15 example 16example 17 example 18 example 19 Oil-extended diene-based rubber a b c eg Evaluation T_(B) (MPa) 22.1 23.1 23.0 22.9 23.4 Wearing resistance 100109 108 112 107

TABLE 7 [Composite constitution (i) using γ-alumina] Dispersion-in-watermethod Example 16 Example 17 Example 18 Example 19 Example 20Oil-extended diene-based rubber a b c e g Diameter of coagulated crumb ◯◯ ◯ ◯ ◯ Evaluation T_(B) (MPa) 22.8 24.3 24.4 24.9 24.1 Wearingresistance 109 115 113 124 122 Comparative Comparative ComparativeComparative Comparative Dry blending example 20 example 21 example 22example 23 example 24 Oil-extended diene-based rubber a b c e gEvaluation T_(B) (MPa) 21.2 22.4 22.6 22.1 22.5 Wearing resistance 100107 107 110 108

TABLE 8 [Composite constitution (i) using calcined clay]Dispersion-in-water method Example 21 Example 22 Example 23 Example 24Example 25 Oil-extended diene-based rubber a b c i j Diameter ofcoagulated crumb ◯ ◯ ◯ ◯ ◯ Evaluation T_(B) (MPa) 23.5 25.1 24.7 24.924.4 Wearing resistance 111 120 118 122 114 Comparative ComparativeComparative Comparative Comparative Dry blending example 25 example 26example 27 example 28 example 29 Oil-extended diene-based rubber a b c ij Evaluation T_(B) (MPa) 21.5 22.6 22.3 22.3 22.4 Wearing resistance 100107 106 111 108

TABLE 9 [Composite constitution (i) using kaolin] Dispersion-in-watermethod Example 26 Example 27 Example 28 Example 29 Example 30Oil-extended diene-based rubber a b c e g Diameter of coagulated crumb ◯◯ ◯ ◯ ◯ Evaluation T_(B) (MPa) 23.4 24.6 24.0 24.4 24.1 Wearingresistance 113 118 114 117 113 Comparative Comparative ComparativeComparative Comparative Dry blending example 30 example 31 example 32example 33 example 34 Oil-extended diene-based rubber a b c e gEvaluation T_(B) (MPa) 21.5 22.6 22.3 22.3 22.3 Wearing resistance 100107 106 111 108

TABLE 10 [Composite constitution (i) using magnesium hydroxide]Dispersion-in-water method Example 31 Example 32 Example 33 Example 34Example 35 Oil-extended diene-based rubber a b c e g Diameter ofcoagulated crumb ◯ ◯ ◯ ◯ ◯ Evaluation T_(B) (MPa) 22.3 23.4 23.3 23.723.0 Wearing resistance 124 140 137 141 135 Comparative ComparativeComparative Comparative Comparative Dry blending example 35 example 36example 37 example 38 example 39 Oil-extended diene-based rubber a b c eg Evaluation T_(B) (MPa) 20.9 22.6 22.4 22.2 22.5 Wearing resistance 100116 114 120 115

TABLE 11 [Composite constitution (i) using titanium oxide]Dispersion-in-water method Example 36 Example 37 Example 38 Example 39Example 40 Oil-extended diene-based rubber a b c i j Diameter ofcoagulated crumb ◯ ◯ ◯ ◯ ◯ Evaluation T_(B) (MPa) 23.6 24.0 23.9 24.224.1 Wearing resistance 111 125 118 121 125 Comparative ComparativeComparative Comparative Comparative Dry blending example 40 example 41example 42 example 43 example 44 Oil-extended diene-based rubber a b c ij Evaluation T_(B) (MPa) 22.5 23.4 23.4 23.5 24.1 Wearing resistance 100107 108 111 106

TABLE 12 [Composite constitution (i) containing aluminium hydroxide]Example in-situ (I) 41 42 43 44 45 46 47 48 49 50 Oil-extendeddiene-based rubber a b c d e f g h i j Diameter of coagulated crumb ◯ ◯◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ Evaluation T_(B) (MPa) 25.0 26.2 25.3 25.6 25.0 24.325.2 24.9 25.0 25.1 Wearing resistance 191 218 211 212 240 210 208 203205 225 Example in-situ (II) 51 52 53 54 55 56 57 58 59 60 Oil-extendeddiene-based rubber a b c d e f g h i j Diameter of coagulated crumb ◯ ◯◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ Evaluation T_(B) (MPa) 24.7 24.8 25.0 25.3 25.1 24.024.9 24.4 24.7 25.0 Wearing resistance 188 216 210 213 237 208 205 201203 223 Example in-situ (III) 61 62 63 64 65 66 67 68 69 70 Oil-extendeddiene-based rubber a b c d e f g h i j Diameter of coagulated crumb ◯ ◯◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ Evaluation T_(B) (MPa) 23.8 26.6 26.1 25.4 25.7 25.025.7 24.6 24.5 26.7 Wearing resistance 170 175 185 182 195 176 184 174176 192

TABLE 13 [Composite constitution (ii) using aluminium hydroxide]Dispersion-in-water method Example 71 Example 72 Example 73 Example 74Example 75 Oil-extended diene-based rubber k l m n o Diameter ofcoagulated crumb ◯ ◯ ◯ ◯ ◯ Evaluation T_(B) (MPa) 23.2 25.2 25.0 24.324.7 Wearing resistance 114 126 123 135 127 Comparative ComparativeComparative Comparative Comparative Dry blending example 45 example 46example 47 example 48 example 49 Oil-extended diene-based rubber k l m no Evaluation T_(B) (MPa) 22.1 23.8 23.6 23.4 23.3 Wearing resistance 100115 113 118 113

TABLE 14 [Composite constitution (ii) using alumina monohydrate]Dispersion-in-water method Example 76 Example 77 Example 78 Example 79Example 80 Oil-extended diene-based rubber k l m n o Diameter ofcoagulated crumb ◯ ◯ ◯ ◯ ◯ Evaluation T_(B) (MPa) 26.2 27.7 27.0 26.727.4 Wearing resistance 109 122 120 126 124 Comparative ComparativeComparative Comparative Comparative Dry blending example 50 example 51example 52 example 53 example 54 Oil-extended diene-based rubber k l m no Evaluation T_(B) (MPa) 24.1 25.2 24.9 25.0 24.9 Wearing resistance 100109 110 114 109

TABLE 15 [Composite constitution (ii) using γ-alumina]Dispersion-in-water method Example 81 Example 82 Example 83 Example 84Example 85 Oil-extended diene-based rubber k l m n o Diameter ofcoagulated crumb ◯ ◯ ◯ ◯ ◯ Evaluation T_(B) (MPa) 24.8 26.5 25.7 25.725.5 Wearing resistance 107 123 119 126 122 Comparative ComparativeComparative Comparative Comparative Dry blending example 55 example 56example 57 example 58 example 59 Oil-extended diene-based rubber k l m no Evaluation T_(B) (MPa) 23.5 24.7 24.6 24.4 24.5 Wearing resistance 100108 107 111 107

TABLE 16 [Composite constitution (ii) using calcined clay]Dispersion-in-water method Example 86 Example 87 Example 88 Example 89Example 90 Oil-extended diene-based rubber k l m n o Diameter ofcoagulated crumb ◯ ◯ ◯ ◯ ◯ Evaluation T_(B) (MPa) 24.7 26.6 26.3 26.026.1 Wearing resistance 108 125 122 127 123 Comparative ComparativeComparative Comparative Comparative Dry blending example 60 example 61example 62 example 63 example 64 Oil-extended diene-based rubber k l m no Evaluation T_(B) (MPa) 23.9 25.0 24.9 24.9 25.3 Wearing resistance 100109 108 113 109

TABLE 17 [Composite constitution (ii) using kaolin] Dispersion-in-watermethod Example 91 Example 92 Example 93 Example 94 Example 95Oil-extended diene-based rubber k l m n o Diameter of coagulated crumb ◯◯ ◯ ◯ ◯ Evaluation T_(B) (MPa) 25.5 26.3 26.1 26.6 25.9 Wearingresistance 114 126 123 132 123 Comparative Comparative ComparativeComparative Comparative Dry blending example 65 example 66 example 67example 68 example 69 Oil-extended diene-based rubber k l m n oEvaluation T_(B) (MPa) 23.3 24.2 24.5 24.1 24.4 Wearing resistance 100110 109 114 110

TABLE 18 [Composite constitution (ii) using magnesium hydroxide]Dispersion-in-water method Example 96 Example 97 Example 98 Example 99Example 100 Oil-extended diene-based rubber k l m n o Diameter ofcoagulated crumb ◯ ◯ ◯ ◯ ◯ Evaluation T_(B) (MPa) 24.4 25.4 24.7 25.125.5 Wearing resistance 118 141 139 146 138 Comparative ComparativeComparative Comparative Comparative Dry blending example 70 example 71example 72 example 73 example 74 Oil-extended diene-based rubber k l m no Evaluation T_(B) (MPa) 23.2 24.2 24.2 24.1 23.8 Wearing resistance 100120 119 126 118

TABLE 19 [Composite constitution (ii) using titanium oxide]Dispersion-in-water method Example 101 Example 102 Example 103 Example104 Example 105 Oil-extended diene-based rubber k l m n o Diameter ofcoagulated crumb ◯ ◯ ◯ ◯ ◯ Evaluation T_(B) (MPa) 24.7 26.5 26.1 26.325.7 Wearing resistance 109 122 120 126 122 Comparative ComparativeComparative Comparative Comparative Dry blending example 75 example 76example 77 example 78 example 79 Oil-extended diene-based rubber k l m no Evaluation T_(B) (MPa) 24.2 25.3 25.1 25.3 24.9 Wearing resistance 100108 107 112 107

TABLE 20 [Composite constitution (ii) containing aluminium hydroxide]in-situ (I) Example 106 Example 107 Example 108 Example 109 Example 110Oil-extended diene-based rubber k l m n o Diameter of coagulated crumb ◯◯ ◯ ◯ ◯ Evaluation T_(B) (MPa) 26.2 27.0 26.9 26.3 26.4 Wearingresistance 146 173 168 172 169 in-situ (III) Example 111 Example 112Example 113 Example 114 Example 115 Oil-extended diene-based rubber k lm n o Diameter of coagulated crumb ◯ ◯ ◯ ◯ ◯ Evaluation T_(B) (MPa) 25.326.9 26.4 26.3 26.4 Wearing resistance 145 161 162 169 166

TABLE 21 [Composite constitution (iii) using aluminium hydroxide]Dispersion-in-water method Example 116 Example 117 Example 118 Example119 Example 120 Oil-extended diene-based rubber k l m n o Diameter ofcoagulated crumb ◯ ◯ ◯ ◯ ◯ Evaluation T_(B) (MPa) 14.2 16.5 16.2 16.316.4 Wearing resistance 173 227 221 255 235 Comparative ComparativeComparative Comparative Comparative Dry blending example 80 example 81example 82 example 83 example 84 Oil-extended diene-based rubber k l m no Evaluation T_(B) (MPa) 9.1 12.0 12.1 11.8 11.7 Wearing resistance 100153 149 184 144

TABLE 22 [Composite constitution (iii) using alumina monohydrate]Dispersion-in-water method Example 121 Example 122 Example 123 Example124 Example 125 Oil-extended diene-based rubber a b c e g Diameter ofcoagulated crumb ◯ ◯ ◯ ◯ ◯ Evaluation T_(B) (MPa) 18.7 20.7 21.5 20.221.2 Wearing resistance 150 167 172 183 167 Comparative ComparativeComparative Comparative Comparative Dry blending example 85 example 86example 87 example 88 example 89 Oil-extended diene-based rubber a b c eg Evaluation T_(B) (MPa) 11.9 14.1 14.3 13.7 14.0 Wearing resistance 100140 139 149 137

TABLE 23 [Composite constitution (iii) containing aluminium hydroxide]in-situ (I) Example 126 Example 127 Example 128 Example 129 Example 130Oil-extended diene-based rubber k l m n o Diameter of coagulated crumb ◯◯ ◯ ◯ ◯ Evaluation T_(B) (MPa) 22.1 23.8 24.1 23.7 23.1 Wearingresistance 333 408 402 429 406 in-situ (III) Example 131 Example 132Example 133 Example 134 Example 135 Oil-extended diene-based rubber k lm n o Diameter of coagulated crumb ◯ ◯ ◯ ◯ ◯ Evaluation T_(B) (MPa) 20.522.5 23.4 22.3 23.1 Wearing resistance 314 398 392 419 379

TABLE 24 [Composite constitution (iv) using aluminium hydroxide]Dispersion-in-water method Example 136 Example 137 Example 138 Example139 Example 140 Oil-extended diene-based rubber a b c e g Diameter ofcoagulated crumb ◯ ◯ ◯ ◯ ◯ Evaluation T_(B) (MPa) 23.8 24.6 25.3 24.724.4 Wearing resistance 119 130 135 142 126 Comparative ComparativeComparative Comparative Comparative Dry blending example 90 example 91example 92 example 93 example 94 Oil-extended diene-based rubber a b c eg Evaluation T_(B) (MPa) 21.7 23.0 22.9 22.5 23.1 Wearing resistance 100118 115 124 114

TABLE 25 [Composite constitution (iv) using alumina monohydrate]Dispersion-in-water method Example 141 Example 142 Example 143 Example144 Example 145 Oil-extended diene-based rubber a b c e g Diameter ofcoagulated crumb ◯ ◯ ◯ ◯ ◯ Evaluation T_(B) (MPa) 25.5 26.4 26.2 26.326.5 Wearing resistance 115 133 137 141 113 Comparative ComparativeComparative Comparative Comparative Dry blending example 95 example 96example 97 example 98 example 99 Oil-extended diene-based rubber a b c eg Evaluation T_(B) (MPa) 24.1 25.1 25.2 24.9 25.1 Wearing resistance 100115 112 120 113

TABLE 26 [Composite constitution (iv) using γ-alumina]Dispersion-in-water method Example 146 Example 147 Example 148 Example149 Example 150 Oil-extended diene-based rubber a b c e g Diameter ofcoagulated crumb ◯ ◯ ◯ ◯ ◯ Evaluation T_(B) (MPa) 24.8 25.5 26.0 26.426.1 Wearing resistance 111 128 133 139 128 Comparative ComparativeComparative Comparative Comparative Dry blending example 100 example 101example 102 example 103 example 104 Oil-extended diene-based rubber a bc e g Evaluation T_(B) (MPa) 22.8 23.9 24.1 23.8 24.0 Wearing resistance100 114 110 116 111

TABLE 27 [Composite constitution (iv) using calcined clayDispersion-in-water method Example 151 Example 152 Example 153 Example154 Example 155 Oil-extended diene-based rubber a b c e g Diameter ofcoagulated crumb ◯ ◯ ◯ ◯ ◯ Evaluation T_(B) (MPa) 24.6 25.8 25.7 25.626.0 Wearing resistance 107 129 120 136 135 Comparative ComparativeComparative Comparative Comparative Dry blending example 105 example 106example 107 example 108 example 109 Oil-extended diene-based rubber a bc e g Evaluation T_(B) (MPa) 22.7 24.2 24.0 23.8 24.0 Wearing resistance100 112 110 116 113

TABLE 28 [Composite constitution (iv) containing aluminium hydroxide]in-situ (I) Example 156 Example 157 Example 158 Example 159 Example 160Oil-extended diene-based rubber a b c e g Diameter of coagulated crumb ◯◯ ◯ ◯ ◯ Evaluation T_(B) (MPa) 25.3 27.0 26.7 26.4 26.4 Wearingresistance 149 175 176 185 169 in-situ (III) Example 161 Example 162Example 163 Example 164 Example 165 Oil-extended diene-based rubber a bc e g Diameter of coagulated crumb ◯ ◯ ◯ ◯ ◯ Evaluation T_(B) (MPa) 25.526.3 26.4 26.3 26.5 Wearing resistance 138 163 162 171 173

TABLE 29 [Composite constitution (v) using aluminium hydroxide]Dispersion-in-water method Example 166 Example 167 Example 168 Example169 Example 170 Oil-extended diene-based rubber p q r s t Diameter ofcoagulated crumb ◯ ◯ ◯ ◯ ◯ Evaluation T_(B) (MPa) 14.2 16.5 16.2 16.316.4 Wearing resistance 173 227 221 255 235 Comparative ComparativeComparative Comparative Comparative Dry blending example 110 example 111example 112 example 113 example 114 Oil-extended diene-based rubber p qr s t Evaluation T_(B) (MPa) 18.6 20.2 19.9 19.7 20.0 Wearing resistance100 111 110 114 110

TABLE 30 [Composite constitution (v) using alumina monohydrate]Dispersion-in-water method Example 171 Example 172 Example 173 Example174 Example 175 Oil-extended diene-based rubber p q r s t Diameter ofcoagulated crumb ◯ ◯ ◯ ◯ ◯ Evaluation T_(B) (MPa) 18.7 20.7 21.5 20.221.2 Wearing resistance 150 167 172 183 167 Comparative ComparativeComparative Comparative Comparative Dry blending example 115 example 116example 117 example 118 example 119 Oil-extended diene-based rubber p qr s t Evaluation T_(B) (MPa) 20.4 21.5 21.5 21.1 21.4 Wearing resistance100 107 108 110 107

TABLE 31 [Composite constitution (v) containing aluminum hydroxide]in-situ (I) Example 176 Example 177 Example 178 Example 179 Example 180Oil-extended diene-based rubber p q r s t Diameter of coagulated crumb ◯◯ ◯ ◯ ◯ Evaluation T_(B) (MPa) 22.1 23.8 24.1 23.7 23.1 Wearingresistance 333 408 402 429 406 in-situ (III) Example 181 Example 182Example 183 Example 184 Example 185 Oil-extended diene-based rubber p qr s t Diameter of coagulated crumb ◯ ◯ ◯ ◯ ◯ Evaluation T_(B) (MPa) 20.522.5 23.4 22.3 23.1 Wearing resistance 314 398 392 419 3795. Effect of Examples 1 to 1855-1. Size of the Diene-Based Rubber-Inorganic Compound Composite

The results from Tables 5 to 31, crumbs having high dispersibility foreach kinds of inorganic compound and having an average particle diameterof 5 mm or more could be obtained both by the production process using ahomogenizer and by the processes according to in-situ (I), (II) and(III).

5-2. Evaluation of the Vulcanized Rubber

Tables 32 to 34 show the results of evaluation shown in Tables 5 to 31collectively. It can be seen from the tables that since compositeshaving high dispersibility of the inorganic compounds are used in eachof the examples compared with corresponding comparative examples, T_(B)value (tensile strength) is high and the wearing resistance isexcellent. TABLE 32 Aluminium hydroxide Dispersion- in-water Dryblending method in-situ (I) in-situ (II) in-situ (III) Formulation; AT_(B) (MPa) 20.1 21.5 25.0 24.7 23.8 Oil-extended diene-based Wearingresistance 100 122 191 188 170 rubber; a Formulation; B T_(B) (MPa) 22.123.2 26.2 — 25.3 Non-oil-extended diene- Wearing resistance 100 114 146— 145 based rubber; k Formulation; C T_(B) (MPa) 9.1 14.2 22.1 — 20.5Non-oil-extended diene- Wearing resistance 100 173 333 — 314 basedrubber; k Formulation; D T_(B) (MPa) 21.7 23.8 25.3 — 25.5 Oil-extendeddiene-based Wearing resistance 100 119 149 — 138 rubber; a Formulation;E T_(B) (MPa) 18.6 20.0 22.8 — 22.0 Non-oil-extended diene- Wearingresistance 100 107 135 — 131 based rubber;Note:Each wearing resistance data is represented by a data in dry blending ofeach formulation, where INDEX = 100 in dry blending.

TABLE 33 Alumina monohydrate γ-Alumina Calcined clay Dispersion-Dispersion- Dispersion- in-water in-water in-water Dry blending methodDry blending method Dry blending method Formulation; A T_(B) (MPa) 22.124.7 21.2 22.8 21.5 23.5 Oil-extended diene-based Wearing resistance 100112 100 109 100 111 rubber; a Formulation; B T_(B) (MPa) 24.1 26.2 23.524.8 23.9 24.7 Non-oil-extended diene- Wearing resistance 100 109 100107 100 106 based rubber; k Formulation; C T_(B) (MPa) 11.9 18.7 — — — —Non-oil-extended diene- Wearing resistance 100 150 — — — — based rubber;k Formulation; D T_(B) (MPa) 24.1 25.5 22.8 24.8 22.7 24.6 Oil-extendeddiene-based Wearing resistance 100 115 100 111 100 111 rubber; aFormulation; E T_(B) (MPa) 20.4 22.3 — — — — Non-oil-extended diene-Wearing resistance 100 108 — — — — based rubber; pNote:Each wearing resistance data is represented by a data in dry blending ofeach formulation, where INDEX = 100 in dry blending.

TABLE 34 Kaolin Magnesium hydroxide Titanium oxide Dispersion-Dispersion- Dispersion- Dry blending method Dry blending method Dryblending method Formulation; A T_(B) (MPa) 21.4 23.4 20.9 22.3 22.5 23.6Oil-extended diene-based Wearing resistance 100 113 100 124 100 111rubber; a Formulation; B T_(B) (MPa) 23.3 25.5 23.2 24.4 24.2 24.7Non-oil-extended diene- Wearing resistance 100 114 100 118 100 109 basedrubber; kNote:Each wearing resistance data is represented by a data in dry blending ofeach formulation, where INDEX = 100 in dry blending.6. Production of Diene-Based Rubber-Aluminium Hydroxide Composite (II)

The oil-extended diene-based rubber a or e (Table 1) and thenon-oil-extended diene-based rubber k (Table 2) obtained described abovewere used as the aqueous dispersion such that the content of the rubbercomponent in each of them was 100 parts, and diene-basedrubber-aluminium hydroxide composites were produced such that thecontent ratios for the rubber component and an aluminium hydroxideformed were in the values shown in Table 35 for the two kinds ofcomposite constitutions (vi) and (vii) shown in Table 35. For example,in a case of (vi) in Table 35, they were controlled properly so as toproduce a composite containing 30 parts of aluminium hydroxide to 137.5parts of an oil-extended diene rubber containing 100 parts of adiene-based rubber. TABLE 35 Composite constitution (vi) (vii) Rubbercomponent (parts by Oil-extended diene-based 137.5* mass) rubber; a, eNon-oil-extended diene- 100 based rubber; k Aluminium hydroxide 30 20(parts by mass)*It contains 100 parts by mass of diene-based rubber.6-1. Method by In-Situ (IV)

EXAMPLE 186

For the composite constitution (vi) shown in Table 35, 380 parts of 10%sulfuric acid was added to 2,570 parts of an aqueous 2.4% solution ofsodium aluminate (0.9% being converted as Al₂O₃) and pH was controlledto 7, to obtain an aluminium-containing suspension comprising aluminiumhydroxide as a main component. After that, 538.5 parts of an emulsifieddispersion of the oil-extended diene-based rubber a (containing 100parts of a diene-based rubber and 37.5 parts of an aromatic oil) wasadded to the aluminium-containing suspension, and mixed by using astirrer to form crumbs. The mixture had pH of 7.5. Then, pH of theliquid mixture was controlled to 7 with addition of 10% sulfuric acidand coagulation was completed. The time required for controlling pH wasabout 3 minutes. Thus the supernatant of the resultant crumb-containingsolution was clear and it confirmed that coagulation product wasentirely precipitated and the diene-based rubber and aluminium hydroxidewere co-coagulated.

The obtained coagulation product was separated by filtration and furtherwashed with water and then dried by a hot blow drier to obtain anoil-extended diene-based rubber-aluminium hydroxide composite. Theresultant composite was ashed and aluminium hydroxide/aluminiumsulfate=30/10 (phr) based on the content of the inorganic compoundcalculated from the ash content and the result of measurement by anX-ray micro-analyzer (XMA) (refer to Table 36).

EXAMPLE 187

An oil-extended diene-based rubber-aluminium oxide composite wasproduced in the same manner as Example 186 except for using oil-extendeddiene-based rubber e instead of the oil-extended diene-based rubber afor the composition constitution (vi) shown in Table 35 (refer to Table36).

EXAMPLE 188

An oil-extended diene-based rubber-aluminium oxide composite wasproduced in the same manner as Example 186 except for using oil-extendeddiene-based rubber k instead of the oil-extended diene-based rubber afor the composition constitution (vii) shown in Table 35 (refer to Table36).

EXAMPLE 189

An oil-extended diene-based rubber-aluminium hydroxide composite of thecomposite constitution (vi) was produced in the same manner as Example186 except for controlling pH of the aluminium-containing suspension to5.5 (refer to Table 36).

EXAMPLE 190

An oil-extended diene-based rubber-aluminium hydroxide composite of thecomposite constitution (vi) was produced in the same manner as Example189 except for using the oil-extended diene-based rubber e instead ofthe oil-extended diene-based rubber a (refer to Table 36). TABLE 36Example Example Example in-situ (IV), pH7 186 187 188 Oil-extendeddiene-based rubber a e k Aluminium hydroxide (phr) 30 30 20 Aluminiumsulfate (phr) 10 10 6 Yield (%) 75 75 77 Evaluation T_(B) (MPa) 24.824.6 25.1 Wearing resistance 188 207 150 Example Example in-situ (IV),pH5.5 189 190 Oil-extended diene-based rubber a e Aluminium hydroxide(phr) 30 30 Aluminium sulfate (phr) 15 15 Yield (%) 67 67 EvaluationT_(B) (MPa) 24.2 24.1 Wearing resistance 169 183 Compara- Compara-Compara- tive tive tive example example example in-situ (IV), pH4 121122 123 Oil-extended diene-based rubber a e k Aluminium hydroxide (phr)30 30 20 Aluminium sulfate (phr) 20 21 13 Yield (%) 60 59 61 EvaluationT_(B) (MPa) 21.1 21.3 20 Wearing resistance 146 156 122

COMPARATIVE EXAMPLE 120

538.5 parts of an emulsified dispersion of an oil-extended diene-basedrubber a (containing 100 parts of a diene-based rubber and 37.5 parts ofan aromatic oil) was added to 2,570 parts of an aqueous 2.4% solution ofsodium aluminium (0.9% being converted as Al₂O₃, pH: about 13) and mixedby using a stirrer. The mixture had pH between 12 and 13. After that,10% sulfuric acid was added to control to pH 4 and coagulation wascompleted. The time required for controlling pH was about 5 minutes. Alarge amount of suspended solids (diene-based rubber) were present inthe resultant product and coagulation product was inhomogeneous.

COMPARATIVE EXAMPLE 121

Coagulation was conducted in the same manner as Comparative Example 120except for changing the addition time for 10% sulfuric acid to 20minutes. In this case, most of coagulation products were precipitatedalthough suspended solids of the diene-based rubber were slightlyobserved. Further, aluminium hydroxide/aluminium sulfate=30/20 (phr) wasobtained in the same manner as in Example 186 (refer to Table 36).

COMPARATIVE EXAMPLE 122 AND COMPARATIVE EXAMPLE 123

An oil-extended diene-based rubber-aluminium hydroxide composite ornon-oil-extended diene-based rubber-aluminium hydroxide composite wasproduced in the same manner as Comparative Example 121 except for usingthe oil-extended diene-based rubber e or non-oil-extended diene-basedrubber k instead of the oil-extended diene-based rubber a (refer toTable 36).

6-2. Method by In-Situ (V)

EXAMPLE 191

For the composite constitution (vi) shown in Table 35, 380 parts of 10%sulfuric acid was added to 2,570 parts of an aqueous 2.4% solution ofsodium aluminate (0.9% being converted as Al₂O₃) and pH was controlledto 7, to obtain an aluminium-containing suspension comprising aluminiumhydroxide as a main component. After that, a prescribed amount of 30% of538.5 parts of an emulsified dispersion of the oil-extended diene-basedrubber a which is containing 100 parts of the diene-based rubber and37.5 parts of an aromatic oil, (that is corresponding to 143 parts ofthe diene-based rubber having solid concentration of 21% and 11.3 partsof the aromatic oil), and the above aluminium-containing suspension weremixed while stirring to form crumbs. Then, the emulsified dispersion inan amount corresponding to the remaining 70% was added and mixed to formcrumbs further. The liquid mixture had pH of 7.7. And pH of the liquidmixture was controlled to 7 with addition of 10% sulfuric acid andcoagulation was completed. The time required for controlling pH wasabout 3 minutes. Thus the supernatant of the resultant crumb-containingsolution was clear and it confirmed that a coagulation product wasentirely precipitated and the diene-based rubber and aluminium hydroxidewere co-coagulated.

The obtained coagulation product was separated by filtration and furtherwashed with water and then dried by a hot blow drier to obtain anoil-extended diene-based rubber-aluminium hydroxide composite. Theresultant composite was ashed and aluminium hydroxide/aluminiumsulfate=30/10 (phr) in the same manner as Example 186 (refer to Table37).

COMPARATIVE EXAMPLE 124

A prescribed amount of 30% of 538.5 parts of an emulsified dispersion ofthe oil-extended diene-based rubber a which is containing 100 parts ofthe diene-based rubber and 37.5 parts of an aromatic oil, (that iscorresponding to 30 parts of the diene-based rubber and 11.3 parts ofthe aromatic oil) was added and mixed to 2,570 parts of an aqueous 2.4%solution of sodium aluminate (0.9% being converted as Al₂O₃) to formcrumbs. After that, the emulsified dispersion in an amount correspondingto the remaining 70% was added and mixed to form crumbs further. Themixture had pH of 12. And pH of the liquid mixture was controlled to 4with addition of 10% sulfuric acid and coagulation was completed. Thetime required for controlling pH was about 5 minutes. A large amount ofsuspended solids (diene-based rubber) were present in the resultantproduct and the coagulation product was inhomogeneous.

COMPARATIVE EXAMPLE 125

Coagulation was conducted in the same manner as Comparative Example 124except for changing the addition time of 10% sulfuric acid to 20minutes. In this case, most of coagulation products were precipitatedalthough suspended solids of diene-based rubber were slightly observed.Further, aluminium hydroxide/aluminium sulfate=30/21 (phr) was obtainedin the same manner as in described above (refer to Table 37). TABLE 37in-situ (V), pH7 Example 191 Oil-extended diene-based rubber a Aluminiumhydroxide (phr) 30 Aluminium sulfate (phr) 10 Yield (%) 75 EvaluationT_(B) (MPa) 24.5 resistance 187 Comparative in-situ (V), pH4 example 125Oil-extended diene-based rubber a Aluminium hydroxide (phr) 30 Aluminiumsulfate (phr) 21 Yield (%) 59 Evaluation T_(B) (MPa) 22.4 Wearingresistance 1446-3. Method by In-Situ (VI)

EXAMPLE 192

For the composite constitution (vi) shown in Table 35, 500 parts of 10%sulfuric acid was added to an aqueous solution controlled to pH 14 withaddition of 95 parts sodium hydroxide to 2,660 parts of an aqueous 3.0%solution of aluminium sulfate (Al₂O₃ conversion=0.9%) and pH wascontrolled to 7, to obtain an aluminium-containing suspension comprisingaluminium hydroxide as a main component. After that, 538.5 parts of anemulsified dispersion liquid of the oil-extended diene-based rubber a(containing 100 parts of a diene-based rubber and 37.5 parts of anaromatic oil) were added to the aluminium-containing suspension, andmixed by using a stirrer to form crumbs. The pH for the liquid mixturewas 7.7. Then, pH of the liquid mixture was controlled to 7 withaddition of 10% sulfuric acid and coagulation was completed. The timerequired for controlling pH was about 3 minutes. The supernatant of theresultant crumb-containing solution was clear and it confirmed thatcoagulation product was entirely precipitated and the diene-based rubberand the aluminium hydroxide were co-coagulated.

The obtained coagulation product was separated by filtration and furtherwashed with water and then dried by a hot blow drier to obtain anoil-extended diene-based rubber-aluminium hydroxide composite. In thesame manner as Example 186, aluminium hydroxide/aluminium sulfate=30/13(phr) was obtained (refer to Table 38).

COMPARATIVE EXAMPLE 126

538.5 parts of an emulsified dispersion liquid of an oil-extendeddiene-based rubber a (containing 100 parts of a diene-based rubber and37.5 parts of an aromatic oil) were added to an aqueous solutionprepared by adding 95 parts of sodium hydroxide to 2,660 parts of anaqueous 3.0% solution of aluminium sulfate (Al₂O₃ conversion=0.9%) andcontrolled to pH 14 and mixed by using a stirrer. The liquid mixture hadpH between 12 and 13. After that, 10% sulfuric acid was added to controlpH to 4 and coagulation was completed. The time required for controllingpH was about 5 minutes. A large amount of suspended solids considered tobe diene-based rubber were present in the resultant product and wereinhomogeneous.

COMPARATIVE EXAMPLE 127

Coagulation was conducted in the same manner as Comparative Example 126except for changing the addition time of 10% sulfuric acid to 20minutes. In this case, most of coagulation products were precipitatedalthough suspended solids of diene-based rubber were slightly observed.Further, aluminium hydroxide/aluminium sulfate=30/25 (phr) was obtainedin the same manner as described above (refer to Table 38). TABLE 38in-situ (VI), pH7 Example 192 Oil-extended diene-based rubber aAluminium hydroxide (phr) 30 Aluminium sulfate (phr) 13 Yield (%) 70Evaluation T_(B) (MPa) 24.1 Wearing resistance 178 Comparative in-situ(VI), pH4 example 127 Oil-extended diene-based rubber a Aluminiumhydroxide (phr) 30 Aluminium sulfate (phr) 25 Yield (%) 55 EvaluationT_(B) (MPa) 21.3 Wearing resistance 1327. Preparation of Rubber Composition

Rubber compositions were prepared by using composites produced inExamples 186 to 192 and Comparative Examples 121 to 123, 125 and 127described above and ingredients described above, and kneading above twostages in accordance with formulations A and B in Table 4. In thisrubber compositions, “inorganic compound” in Table 4 means aluminiumhydroxide contained in the composites.

COMPARATIVE EXAMPLES 128 TO 130

Rubber compositions were prepared by using oil-extended diene-basedrubbers a and e or non-oil-extended diene-based rubber k, andcommercially available aluminium hydroxide powder (trade name; “HIGILITEH-43M” manufactured by Showa Denko K. K., average particle diameter; 0.6μm) by dry blending in accordance with the formulation in Table 4.

8. Evaluation of Performance

The rubber compositions obtained as described above were evaluated inthe same manner as in 4 above and the results were shown in Tables 36 to39. TABLE 39 Compara- Compara- Compara- tive tive tive example exampleexample Dry blending 128 129 130 Oil-extended diene-based rubber a e kAluminium hydroxide (phr) 30 30 20 Aluminium sulfate (phr) — — —Evaluation T_(B) (MPa) 20.1 21.6 22.1 Wearing resistance 100 100 1009. Effect of Examples 186 to 1929-1. Content of Aluminium Hydroxide

As the results from Table 36, Comparative Example 121 and ComparativeExample 122 using an aluminium-containing solution controlled to pH 4had amounts of formed aluminium sulfate as much as 20 to 21 parts inboth relative to 30 parts of aluminium hydroxide, respectively andyields were about 60% in the production according to in-situ (IV) byusing an oil-extended diene-based rubber. In addition, in Example 189and Example 190 using an aluminium-containing suspension controlled topH 5.5, amount of formed aluminium sulfate were 15 parts in bothrelative to 30 parts of aluminium hydroxide which were slightlyimproved. On the other hand, in Example 186 and Example 187 using analuminium-containing solution controlled to pH 7, purities of aluminiumhydroxide were improved and the amounts of formed aluminium sulfate wereas less as 10 parts in both based on 30 parts of aluminium hydroxide.

Additionally, also in a case of using a non-oil-extended diene-basedrubber, while an aluminium-containing solution controlled to pH 4 wasused and the yield was as low as 61% in Comparative Example 123, it wasincreased up to 77% in Example 188 controlled to pH 7.

As the results from Table 37, Comparative Example 125 using analuminium-containing solution controlled to pH 4 had an amount of formedaluminium sulfate as much as 21 parts relative to 30 parts of aluminiumhydroxide according to in-situ (V). On the other hand, in Example 191using an aluminium-containing solution controlled to pH 7, the amount offormed aluminium sulfate was as less as 10 parts and the content ofaluminium hydroxide was improved. In addition, as the results from Table38, Comparative Example 127 using an aluminium-containing solutioncontrolled to pH 4 had an amount of formed aluminium sulfate as much as25 parts based on 30 parts of aluminium hydroxide in the productionaccording to in-situ (VI). On the other hand, in Example 192 using analuminium-containing solution controlled to pH 7, an amount of formedaluminium sulfate was as less as 13 parts and the content of aluminiumhydroxide was improved.

9-2. Evaluation of the Vulcanized Rubber

Table 40 summarizes the results of evaluation in Tables 36 to 39. Theresult of Table 40 shows that since the amount of aluminium sulfate asan impurity was low, T_(B) value (tensile strength) was high and wearingresistance was excellent in each of the Examples compared withcorresponding Comparative Examples. For example, the vulcanized rubberobtained from the rubber composition prepared in accordance with theformulation A in Table 4 by using the oil-extended diene-based rubber aobtained in the production according to in-situ (IV), T_(B) wasincreased as 21.1→24.2→24.8 MPa as pH increased higher and, at the sametime, the wearing resistance was also improved as 146→169→188 (indexbased on 100 for dry blend data). Similar trend was also confirmed forother examples. TABLE 40 Dry in-situ (IV) in-situ (V) in-situ (VI)blending pH7 pH5.5 pH4 pH7 pH4 pH7 pH4 Formulation; A T_(B) (MPa) 20.124.8 24.2 21.1 24.5 22.4 24.1 21.3 Oil-extended diene-based Wearingresistance 100 188 169 146 187 144 178 132 rubber; a Formulation; AT_(B) (MPa) 21.6 24.6 24.1 21.3 — — — — Oil-extended diene-based Wearingresistance 100 207 183 156 — — — — rubber; e Formulation; B T_(B) (MPa)22.1 25.1 — 20.0 — — — — Non-oil-extended diene- Wearing resistance 100150 — 122 — — — — based rubber; kNote:Each wearing resistance data is represented by a data in dry blending ofeach formulation, where INDEX = 100 in dry blending.

EFFECT OF THE INVENTION

According to the present invention, a diene-based rubber-inorganiccompound composite having high dispersibility of the inorganic compoundcan be produced at high productivity. Since the size of the crumbdiameter of the composite obtained by the coagulation step is as largeas 5 mm or more, the operation efficiency during production of thediene-based rubber-inorganic compound composite is further improved. Inaddition, the use of the obtained diene-based rubber-inorganic compoundcomposite according to the production process of the present inventionleads to a rubber composition for providing a rubber product havingexcellent characteristics such as wearing resistance.

Further, according to another invention, a diene-based rubber-inorganiccompound composite in which aluminium oxide is dispersed at high contentand homogeneously can be produced at high productivity. Controlling ofpH of the aluminium-containing suspension in a range between 5.1 and 8.4(weakly acidic—neutral—weakly alkaline property) can provide excellentoperation efficiency and safety, lower an amount of impurities such asaluminium sulfate (Al₂(SO₄)₃) to be formed and can form aluminiumhydroxide at high content.

INDUSTRIAL APPLICABILITY

The diene-based rubber-inorganic compound composite obtained by thepresent invention is utilized as a raw material for a rubber for a tiresuch as a tire tread, as well as various kinds of rubber products suchas a belt, a rubber roll and a hose.

1. A process for producing a diene-based rubber-inorganic compoundcomposite comprising a diene-based rubber and an inorganic compoundrepresented by the following general formula (I), comprising a step ofmixing an inorganic compound and/or a material capable of forming saidinorganic compound, an anionic compound and a dispersion liquid of adiene-based rubber:wM.xSiO_(y) .zH₂O  (I) wherein M is at least one metal element selectedfrom the group consisting of Al, Mg, Ti and Ca, metal oxide thereof ormetal hydroxide thereof, and w, x, y, and z are an integer of from 1 to5, an integer of from 0 to 10, an integer of from 2 to 5, and an integerof from 0 to 10, respectively.
 2. The process for producing adiene-based rubber-inorganic compound composite according to claim 1,wherein said material capable forming said inorganic compound is atleast one material selected from the group consisting of metal salts,oxoacid salts of metals and organic metal compounds.
 3. The process forproducing a diene-based rubber-inorganic compound composite according toclaim 1, wherein said anionic compound is a compound having a carboxylgroup.
 4. The process for producing a diene-based rubber-inorganiccompound composite according to claim 3, wherein said compound having acarboxyl group is at least one compound selected from the groupconsisting of a rosinate and a salt of a fatty acid.
 5. The process forproducing a diene-based rubber-inorganic compound composite according toclaim 1, wherein said dispersion liquid of said diene-based rubber is adiene-based rubber latex synthesized by emulsion polymerization.
 6. Theprocess for producing a diene-based rubber-inorganic compound compositeaccording to claim 1, comprising a step of co-coagulating saiddiene-based rubber and said inorganic compound from said liquid mixtureobtained in said mixing step by using an electrolyte comprising a metalsalt, a step of separating a coagulation product by filtration, and astep of drying said coagulation product.
 7. The process for producing adiene-based rubber-inorganic compound composite according to claim 1,wherein said diene-based rubber is a diene-based rubber having a polargroup.
 8. The process for producing a diene-based rubber-inorganiccompound composite according to claim 7, wherein said polar group is atleast one kind of group selected from the group consisting of hydroxylgroup, oxy group, alkoxysilyl group, epoxy group, carboxyl group,carbonyl group, oxycarbonyl group, sulfide group, disulfide group,sulfonyl group, sulfinyl group, thiocarbonyl group, imino group, aminogroup, nitrile group, ammonium group, imide group, amide group, hydrazogroup, azo group and diazo group.
 9. The process for producing adiene-based rubber-inorganic compound composite according to claim 1,wherein said inorganic compound represented by the general formula (I)is an inorganic compound represented by the following general formula(II):Al₂O₃ .mSiO₂ .nH₂O  (II) wherein m is an integer from 0 to 4 and n is aninteger from 0 to
 4. 10. The process for producing a diene-basedrubber-inorganic compound composite according to claim 2, wherein saidmetal constituting said metal salt, said oxo acid salt of metal and saidorganic metal compound is aluminium.
 11. The process for producing adiene-based rubber-inorganic compound composite according to claim 1,further comprising a step of mixing a dispersion liquid of a diene-basedrubber to said liquid mixture obtained in said mixing step.
 12. Adiene-based rubber-inorganic compound composite which is obtained by theprocess according to claim
 1. 13. A process for producing a diene-basedrubber-inorganic compound composite comprising a diene-based rubber andaluminium hydroxide, comprising: a step of preparing analuminium-containing suspension whose pH is controlled in a rangebetween 5.1 and 8.4, and a step of mixing said aluminium-containingsuspension and a dispersion liquid of a diene-based rubber toco-coagulate said diene-based rubber and aluminium hydroxide,successively.
 14. The process for producing a diene-basedrubber-inorganic compound composite according to claim 13, comprising astep of adding at least one kind selected from the group consisting anacid and a coagulation accelerator to said co-coagulated liquid mixtureto complete the co-coagulation.
 15. The process for producing adiene-based rubber-inorganic compound composite according to claim 13,wherein said aluminium-containing suspension is prepared by using analuminium salt containing an aluminate.
 16. The process for producing adiene-based rubber-inorganic compound composite according to claim 13,wherein said dispersion liquid of the diene-based rubber is adiene-based rubber latex by emulsion polymerization.
 17. The process forproducing a diene-based rubber-inorganic compound composite according toclaim 13, further comprising a step of separating a coagulation productby filtration and a step of drying said coagulation product.
 18. Theprocess for producing a diene-based rubber-inorganic compound compositeaccording to claim 13, wherein said diene-based rubber is a diene-basedrubber having a polar group.
 19. The process for producing a diene-basedrubber-inorganic compound composite according to claim 18, wherein saidpolar group is at least one kind of group selected from the groupconsisting of hydroxyl group, oxy group, alkoxysilyl group, epoxy group,carboxyl group, carbonyl group, oxycarbonyl group, sulfide group,disulfide group, sulfonyl group, sulfinyl group, thiocarbonyl group,imino group, amino group, nitrile group, ammonium group, imide group,amide group, hydrazo group, azo group and diazo group.
 20. A diene-basedrubber-inorganic compound composite which is obtained by the processaccording to claim 13.